Here's some stuff out of my holdem book on player stereotypes that I make reference to on a recent post on rec.gambling.poker

Chapter 16

Player stereotypes
A common proverb is that there are three kinds of people
1. those who watch things happen
2. those who make things happen
3. those who wonder what happened

Those who watch things happen are called passive players, those who make things happen we call aggressive, and those who wonder what happened, we call clueless. Most tables will have a selection of all three of these kinds of players.
Even within these groups, there are different kinds of players. This is particularly true among aggressive players. Aggression is a characteristic of a good poker player, but not all aggressive players are good players. Some of them play pretty badly, and some of them tend to play well under certain game conditions and don't seem to be able to adjust when the conditions change.
An Initial assessment
The first step in evaluating a player is to categorize him. Players can be generally categorized along two scales: passive-aggressive and loose-tight. The extremes of these scales are readily recognizable. Someone who is extremely loose and aggressive is called a "maniac" because he will bet or raise on just about anything. Someone who is extremely tight and passive is called a "rock' because he will only play sure hands and even then he will play them conservatively and rarely raise. Someone who is extremely loose and passive is called a "calling station" because he will call someone else's bet nearly always but will rarely raise or bet himself. The last extreme type is both tight and aggressive and is called a "stone killer" because he is the one who waits for his opportunities and then pounces on them, making the most money. Most players will not fit into these extreme types, but you will recognize these four characteristics to a greater or lesser extent in every player at a poker table. In addition to the above basic four characteristics, you may want to further categorize players along two other scales: weak-tough and straightforward-tricky.
In order to categorize a player, watch what he does, how he plays, when he calls, when he bets, and when he raises. If you're new to the game, you can also get an assessment of what type of player you are dealing with by watching how other players, the ones who presumably know something about him, react to him. Let us examine the scales and see how various players fit into their respective categories.
The tight-loose player scale
A tight player is one who doesn't get involved in many pots. He's very selective. A loose player plays a lot of hands and continues to play the hand into the later betting rounds
The passive-aggressive scale
A passive player doesn't bet or raise on most hands but will tend to call your bets. An aggressive player is one who bets and raises a lot. If you bet into an aggressive player, he might fold or he might raise, but he's not likely to call.
The weak-tough scale
A weak player is one who always fears the worst. If three flush cards are on the board, he fears a flush. If you bet, he might call, but he won't raise with his straight. A tough player will try to figure out whether or not you actually have a flush. If he doesn't think you have one, he'll raise with his straight. If he does think you have one, he might call or he might fold, depending on how big the pot is. Tough players tend to be hard to read, while weak players tend to be easy to read.
The straightforward-tricky scale
Some players always bet their good hands, always check and call with good draws, and always fold their weak hands and weak draws. You always have a good idea what kind of hand this player holds.
Other players try to get tricky. They'll bet when they don't have much, check and call the flop then raise on the turn when they have a good hand or a great hand. They'll semi-bluff raise a lot. These players are sometimes more difficult to read, but often they overdo the tricky attempts so much that you can read them even more easily than you can a straightforward player. It's just that the clues are backwards.
Narrowing down the hands
But just getting a general category of the player, you can often narrow the range of hands he might have. For example suppose a tight aggressive player just calls pre-flop in early position and the flop is Q* 7* 2* and he suddenly goes berserk by reraising, you have to think what hands are likely.
The hands that are consistent with the play on the flop might be A*Q*, K*Q*, Q*7*. 7*2*, Q*2*, 7*7*, or 2*2*. Most players would slowplay Q*Q* here, even a straightforward player will tend to slowplay a really big hand. You can eliminate most of those hands based on what kinds of hands the type of player would have limped into the pot with from early position.
We can look at these hands and see which are reasonable to just call, pre-flop, in early position. A*Q* and K*Q* are often raised in early position, but at least some of the time they just call, so they are still consistent. Q*7*, 7*2* and Q*2* are not reasonable calls from an early position, except for the loosest of players. 7*7* and 2*2* are candidates for early position play from all but tough or tight players. So that leaves A*Q*, K*Q*, 7*7*, and 2*2*, as his possible hands and, for most players, you can eliminate the 2*2*. This narrows down the field of possibilities quite a bit.
Be aware also of how other players may interpret your betting. If you have an image as a very loose player, then the reraiser might have any queen if he's an aggressive player.
This is just an example of the kind of thinking you need to go through when trying to put a player on a hand. Think about their habits, and use stereotypical thinking if you haven't played with them long enough to know their individual habits. Think about what they think your habits are. A raise from a passive, straightforward player who thinks you're tricky likely has a very different meaning than a raise from a tricky, aggressive player who thinks you're a maniac.
Gathering information
As play goes along, give yourself a running commentary of the events, "she open-raises, he folds, he cold-calls." Don't do it out loud. You must make a lot of mental notes based on this, and you must do this even when you're not in a hand, because in addition to being useful during a hand, it's useful for later hands. You want to see the frequency with which a player sees the flop, the frequency with which a player defends his blinds from raises, and the hands a player open-raises with, raises with, cold-calls with, and just calls with. This in conjunction with the narrowing down the hands above will often give you a good idea of what's going on even when there is no showdown. Stereotype each player, as well as note particular idiosyncrasies of the individuals for use not only now but in future session.
It's useful to get an idea, for each player, what kinds of hands he'll tend to play, and how he'll play them in various situations. Getting this kind of information can take some time, but you should do it for those players who you play with regularly. Write a book on them. Examples of the kind of information you should look for about specific hands are:

1. Will he play pocket pairs less than 6 6, and from what position?

2. When he plays an A xs from UTG, will he limp or raise? What's his cutoff for an open-raise?

3. If he's on the button, will he raise with Axs?
4. Will he raise with less than a nut flush when the flush card hits?
5. Will he raise and reraise with a flush draw when heads up?
6. If he raises with two big cards pre-flop, will he continue betting to the river with just overcards?
You'll have to answer dozens more questions about each player to get that book written, but these questions should be a good start. Once you've answered some of these questions about a player you can sometimes infer the answers to others.
Inferences
Most players are generally consistent in different kinds of situations. The situations don't have to be the same, but the theoretical perspective that the player is using will probably not vary much from situation to situation. So, you can often make a lot of inferences.
For example, if a player tends to frequently raise pre-flop with speculative hands then you can also expect that player to play draws very aggressively. A player who flops a middle sized flush and checks and calls to the river will probably not play draws aggressively. Such a player will also probably not draw to a straight if the board shows a flush draw and will not often draw to a flush if the board is paired. Knowing what kinds of hands a player probably does not have can often be just as valuable as knowing what kinds of hands he does have.
Why do they play?
Earlier in the book I talked about a hunting analogy. Some people enjoy the hunt itself more than the kill. Some people don't see much reason to hunt if you don't kill something. Others just like having the neatest gun. Poker is the same thing. Some play because they want to win money. That's the book players.
Some play because they enjoy the gamble. They want to win also, but they want to create a gamble even more. That's the loose maniac crowd.
There is a third group that doesn't really care if they win, just so long as they "play right". They probably think they want to win, but they really don't care. These are the ones who are always quoting what they've read in a book to the winners, telling them what they did wrong.
Many poker players play simply for the thrill of the gamble. There's a large subset of aggressive players who fall into this category. These players want high-risk games and they'll create them by frequent raises. They are high-risk games because that's what the players want - they made them high risk on purpose. Risk is the point. That does not mean those players are unskilled. Some of them are, of course, but some of them are very skilled. They just use their skills to meet their needs, not yours.
Before you categorize a player beyond the simple dichotomous scales, identify the reason they play - determine their motivating force.
Aggressive players
Tough players tend to be aggressive players, but most aggressive players aren't tough players. Most of them are fairly transparent, and tend not to have very good table judgment.
Macho players
There is a class of aggressive player who just enjoys dominating the game. These players are often tight and aggressive and tricky. There is a certain kind of tight-aggressive-tricky player on tilt who will almost always raise pre-flop with two big cards and limp with big pairs. This certain kind of player will not give up overcards and will be aggressive with them, but will tend to try to trap you with a big pocket pair.
The term tilt comes from a pinball tilt. A player on tilt is one who's playing very badly as a result of some emotional trauma.
If a player like that raises before the flop and I can get heads-up with them, I'll always call with small suited connectors. With a player like that, I'll know whether or not I'm likely best. He'll raise me on the flop when I'm best, and if I call or check then call on the turn he'll call a raise on the river with his Ace King. That's implied odds.

An FPS player on tilt
One of the most aggressive players you'll run across is a Fancy Play Syndrome player on tilt. They can get more inappropriately aggressive than a table maniac. Players with FPS tend to attempt to steal-raise (i.e. a player in late position who open-raises in the hope that everyone will fold and that he can steal the blinds) before the flop too often. The tend to always slow play big hands, like checking a flopped full house. Players with FPS seem to tilt easily. They think of themselves as tough, tricky players, and when their tricks don't work, it angers them. The frequent result is that they start getting more tricky, not less tricky. They make more mistakes, not fewer.
Book Players
Players who tend to play strictly according the recommendations of their favorite poker book tend to self-identify. They'll talk about playable hands, and correct play. They tend to talk about hand groups a lot and will use phrases like pot odds, or implied odds, or dominated hands at the table. They will tend to categorize other players based on how their pre-flop play matches their favorite hand groups. In loose games they tend to overplay pairs on the flop and underplay draws.
These players tend to read about the game a lot. They subscribe to Card Player and Poker Digest magazines. They tend to devote a lot of energy to memorizing the things they read and not much energy to just thinking about the game. They think they think about the game a lot, but they really don't. They are not good players. But, they tend to play fairly tight and are aggressive in passive games. Because of this they do tend to be consistent but small winners in a typical passive game.
Book players tend to select their starting hands from a list, rather then according the game and the opponents. That tends to make them rather easy to read. Such players also tend to be somewhat timid about betting less than the nuts when the board is somewhat scary.
If this kind of player finds himself in a very loose, or a loose-aggressive game, he tends to become a fish. If it's a double- bet on the end game (3/6/12 10/20/40) he approaches the characteristics of a huge fish. When they do think about the game, they tend to think in terms of a contest between a made hand and a draw - sort of a fuzzy two-player game theory perspective. That's a perspective that doesn't work well in a very loose or loose-aggressive game. Also, reverse tells tend to work well against this kind of player - especially if they've labeled you a maniac because they saw you limp reraise six callers from UTG with A* 5*.
When an aggressive player calls
I'm an aggressive player. I raise often and I don't often slow play. You don't have to play with me for very long to realize that I'm an aggressive player. But, having that information doesn't help you much if you don't use it.
I recently played a hand that illustrates the importance of using information when you have it. I had K* J* on the big blind. Two players limped in from middle position, the small blind called. I thought about raising, but decided not to. The reason I didn't was that one of the players who had limped in was an aggressive-tricky player who frequently limped and re-raised with very good hands. The flop was A* 4* 10*. This was a very good flop for me - nut flush draw and a gutshot draw to a nut straight.
The small blind was first and bet. When I saw the flop I decided that I was going to play this hand aggressively, but there were two players behind me who hadn't acted yet, and there was a good chance one of them would raise if I just called. So, I just called, hoping for a raise so I could reraise. My plain failed when both players folded. The turn card was 9*. Now, to my surprise, the small blind checked. He must be on a draw, I thought. I bet. He called. The river card was 2*. I missed my draws, but when the small blind checked I knew he had missed his too. So, I bet. He folded. I got the money.
There is a lesson in the play of this hand. Not from my play, I didn't do anything out of the ordinary, and I probably didn't steal that pot. With my king for high there is a good chance that I had the best hand. The lesson comes from the mistake made by the small blind - he could have easily won that pot.
I have no idea what his hand was, but I hadn't shown any aggression at all. He knew I was a very aggressive player and all I did was call before the flop and on the flop. There was no reason for him to think I had much of a hand at all. In fact, my play should have suggested that my hand was very weak. Why did he check the turn after taking the lead on the flop?
I don't know, but I do know it was a mistake. If he had just continued betting I would have just quietly folded on the river when I missed my draw. The money would have gone to him.
This was a very loose table and few pots were won by a single bet on the flop. It was unusual for the two players behind me to fold. So, his bet on the flop only makes sense if he followed through and continued to bet on the next round. If he had used the information he had about my normal playing style and combined that with the way I was playing that hand, then the natural thing for him to do was just keep betting. He didn't think it through. He didn't really have any kind of plan for the hand an he didn't really pay much attention to what I was doing or not doing. It cost him a pot.
Weak when strong/Strong when weak
A frequent, and very consistent, pattern you'll see in players who have a deception perspective on the game is the weak-when-strong and strong-when-weak pattern. If players like this have a hand in early position like 8*7* and the flop is Q* 8* 8* they will always check-raise. They might check-raise on the flop, or they might wait until the turn, but their initial reaction will be to check. They have a strong hand, their initial impulse is to disguise that by checking, and they will follow that impulse. From your perspective, the beauty of that pattern is that if they bet when the flop looks like that and you have a hand like A* Q* then you can be almost certain that you have the best hand.
Targeting players
It's important to evaluate the table as a unit rather than individual players. Once you sit down at a table, you will need to be concerned with individual players, but in picking a table a focus on individuals can easily steer you away from a good table or even steer you towards a bad table. The presence of a few very good players at a table is not enough of a reason to avoid a table. You don't need to avoid players who are better than you as long as there are a few players at the table who play very badly. Money doesn't flow from all the players straight to the best player at the table. If flows from bad players to all the players who play better than them, even if only slightly better. The bad players at a table will be losing to everyone, even to other bad players. Don't avoid a table just because it has a few very good players.
By the same token, don't sit at a table just because it has a single very bad player. Unless the limit is very high (30/60 or above), a single bad player will not lose enough money to provide more than a mediocre win to a table full of good players. Most of the losses of a single bad player will be soaked up by the rake.
You need at least two bad players at a table to provide enough losses to cover the rake and have enough left over for the rest of the table to book a meaningful win. The key points are that one very bad player isn't enough and the more bad players, the less each one is losing, even though the wins of the good players are increasing. This illustrates two things about loose games (bad players are always loose players). Not only will you win more by playing in very loose games, but also the losers won't go broke as quickly, making loose games longer lasting.
When there is one really bad player at the table
Once you've been playing in a cardroom for a while and have gotten to know the players, you'll sometimes run across a player who plays very badly and is almost certain to just lose all his money. Usually that alone is enough to make it worthwhile to sit in the game, but not always. First you need to make sure that player isn't already close to losing all his money. If he only has a few chips left, then it probably isn't worth sitting in the game unless the game has other characteristics that would make it profitable. Once you've ascertained that the really bad player still has plenty of chips, you need to consider how your skills compare to the other players at the table. As a general guideline:
1. If seven or eight of the other players are all better players than you, then you should pass the game.
2. If six of them are better than you, you can probably still play if the other two players are worse players than you.
3. If five of the players are better than you then you can probably still play if at least one of the other three players is worse than you and the other two are no better than you.
4. If no more than four of the players are better than you, then play.
Target seats and flush draws
As I've mentioned before, in loose games you'll make a large portion of your money from flushes if you play your draws aggressively in a way that keeps many players in on the flop. Seat selection can help you do this.
In a typical lineup of a loose aggressive game you'll often have at least one near maniac player, a player who plays a lot of hands and raises with most of them. You'll also often have a player with some FPS symptoms, in particular you'll find players who like to check-raise a lot. When you have a flush draw on the flop, particularly a flush draw with overcards, you want to get as many players calling as many bets as you can. If you have these two players, a maniac and an FPS player, in the right seats you can do this easily.
If you can sit in between the maniac and the FPS player, with the maniac on your left and the FPS player on your right, then you have a perfect situation to get a maximum number of players to call four bets on the flop.
In fact, if you can arrange that seating, the implied odds you get from potential flushes will be large enough to make any two suited cards worth playing in a loose game. The way to play a flush draw in this situation is to check. The maniac will bet and he'll get a lot of callers because they know he'll beat almost any hand. The FPS player will raise, you can call, the maniac will reraise, everyone who already has one bet in the pot will call. Now, if the FPS player doesn't put in the last raise you can do it. When you can get this kind of ideal seat in the right kind of game, this really works - and it's very profitable.
Picking up tells
One of the things that can help in your game is picking up tells of other flush draws by keeping track of the habits of your opponents.
What hands to they play from early position?
With some tight players, for example, if you have the Queen of a suit, the board has the King, and the player limped in from early position, they do not have a flush draw. That's becuase they wouldn't have come in from early position without at least an Ace, King or Queen, or a pair and they would have raised with any of the hands with an Ace that they would play from that position.
Pay attention to hands players open with from various positions and start building a Turbo Texas Hold 'Em profile of the players who play in your game regularly.
Evaluating players
Poker is about exploitation of weakness. To exploit a weakness, you've first got to identify it. You have to study your opponents.


Here's some more stuff from my chapter on seat selection.

Primary player characteristics
The objective in choosing a seat is to put yourself in a position relative to certain players that enables you to exploit mistakes made by those players. Information gathering is one thing that can help you exploit opponents mistakes, but it's not the only one, and it's often not even the most important.
Picking a good seat is part of an overall strategy of being a lucky player - not because you pick a lucky seat, but because you pick a seat that will give you opportunities. The way your seat can give you opportunities depends on your opponents' habits and the kinds of mistakes they tend to make.
Loose players
A loose player doesn't just play a lot of hands - he tends to get involved with a lot of pots. Loose players play many hands and continue to play into the later betting rounds. Since they play many hands, you get frequent information from them.
Playing a lot of hands means they often play weak hands, so you won't really know a lot about the strength of their hands, but you will know more about the size of the pot and whether you will be getting odds to play speculative hands like J*T*. We'll talk about this more in later chapters.
Aggressive players
An aggressive player is one who bets and raises a lot. If you bet into an aggressive player, he might fold, or he might raise, but he is probably not going to just call. Since aggressive players raise a lot, their raise before you have to act means you can fold hands like A*6*, which are money-makers in multiway pots because of their flush potential but you often don't want to call a raise with that hand. Since you will frequently have to give up that hand on the flop, you would like to know you don't have to invest that money to call a raise.
Loose, aggressive players
Although you usually prefer a loose player on your right and you usually prefer an aggressive player on your right, if a player is both loose and aggressive, you're often better off with them on your left. A player who is too loose, but otherwise plays typically is almost always making the mistake of playing too many hands. A player who plays too aggressively but otherwise plays typically is probably making the mistake of overplaying mediocre or marginal hands. These are different mistakes, but, as we'll see in a minute, you can usually best exploit either of these mistakes by sitting to the players left.
A player who does not play typically at all, but plays both loose and aggressively, might not be making as many mistakes as you might think, depending on the particular game conditions. Whether or not a player who is both loose and aggressive is making many mistakes, you can usually do better with him on your left than on your right. This is because such a player gives you more opportunities for tactical maneuvers in later betting rounds.
Tight players
A tight player isn't going to give up much money. The exception is a tight player who folds too often on the river, but, you won't find many of those. Most tight players are tight in terms of their initial hand selection. They don't play many hands, but typically, once they decide to play a hand they're often committed to it. A tight player is one who doesn't get involved in many pots. He's very selective. Tight players make tight tables. Sometimes tight players will become overcommitted to a hand. Sometimes they give up easily to a bet on the flop or turn, or fail to bet good hands strongly.
Generally you'd prefer a tight player to be on your left. There are two reasons for this. First, although knowing that a tight player is playing a hand does give you some information about the strength of his hand, he seldom plays so you do better with information gathering by having room on your right for loose players and aggresive players. Second, if you're at a tight table you'll get frequent opportunities to open from late position with a raise and steal a tight player's blinds if he's on your left.
Passive players
A passive player doesn't bet or raise on most hands but will tend to call. A player who will almost always call and almost never raise is called a "calling station". You should avoid being a calling station, but you should look for calling stations at your table. It's usually best to have passive players on your left. Since they don't raise much, the information value from acting after them before the flop is fairly small.
Maniac players
A maniac is similar to a player with fancy play syndrome, but a little more extreme. A player with FPS tends to make bets or raises in an attempt to be tricky, and, he does it in situations where it's probably inappropriate and not to his advantage to do so. A maniac often raises just because it's fun. A maniac is not just a loose/aggressive player. He's much more than that. He's a loose/aggressive player with FPS and an itch to gamble. He's loose in that he plays too many hands; he's aggressive in that he tends to raise a lot; but he also tends to raise often in inappropriate situations. He check-raises too much, semi-bluffs too much, bets marginal draws too much. The bottom line is that a maniac likes to play and likes to bet. Maniacs seldom fold, seldom call, and raise at lot - at the slightest provocation. It's best to avoid tables with maniacs if you're a novice. If you're an experienced player, maniacs can be a major source of income. Seat choice relative to the maniac can be very important, and usually depends on the composition of the rest of the table.
One characteristic of maniac players is that you can depend on them to bet or raise with weak hands frequently. Because of that, a maniac is a certain type of loose, aggressive player that is sometimes best to sit 4 or 5 seats on either side of you. This would be the case at a table of generally loose players. When a player has an extreme loose/aggressive style you can usually count on the probability that they will raise before the flop and you can often gain a very large advantage by keying your playing tactics on the flop to a maniac.
When you sit to the right of a maniac, just raise when you want to be reraised, forcing other players to call two bets cold or to fold. If you want to trap other players into calling a raise, check and let the maniac bet so you can raise after other players have called his bet. The ability to manipulate the betting in this way is a huge advantage at a loose table. Let the maniac do the raising for you when you just call with your better hands, and by all means fold anything marginal. Try to get rational aggressive players on your right, and very loose, very aggressive ones on your left.
Players who bluff too much
Anytime you have a player who habitually makes the same mistake, such as bluffing too much, you want to be able to encourage them to continue to make the mistake. If a player bluffs too much, you want to encourage them to bluff. Nothing encourages a bluff as much as a check. Especially if you're in a game where the betsize doubles on the river, you want habitual bluffers on your left. The reason is, of course, you can pick up many extra bets by checking and calling if a habitual bluffer is acting after you.
Drunks
Drunks are almost always loose players. Sometimes passive, sometimes aggressive, always loose. So, if you have to play at a table with a drunk, sit on their left, but, the best strategy for a table with a drunk is often to just move to another table - don't play. They can be counted on to lose their money, but they slow the game down to a snails pace and tend to be quick to anger - neither of which is good for the game. Avoid drunks, but sit on their left if you can't