Slow play is an interesting topic, because it is a second-level poker strategy (i.e., a strategy based on the predicted reactions of other players rather than based on the value of your own hand) and yet it is one that even novice players are aware of and tend to try to incorporate into their game. As a result, however, a lot of slow play occurs without much thought. Here are some considerations about slow playing a hand.
If I were to write a guideline about slowplaying, it would be this-- it is profitable to slow play when these three things are all true: (a) Hero's hand is extremely likely to defeat Villain's or Villains' hand(s) even if Villain(s) improve their hand(s) on the remaining streets; (b) Villain(s) are more likely to fold rather than calling or raising a bet by Hero; and (c) Villain(s) are likely to bet in response to a check by Hero.
Let's examine these things in turn.
First, Hero's hand is extremely likely to win even if Villain improves on the remaining streets. This is where people really lose money by slow playing. When you are slow playing, you are giving your opponents the option to see additional streets for free. Thus, let's say you have 66 and the flop comes up Ad Kd 6s. If you slow play your set and your opponent has AK, QJ, or two diamonds, you are allowing him a free chance (or possibly even two free chances) to draw a card that will beat your hand. Now, the odds are he won't do it. But you have the option of putting a high price on his draw and forcing him to either make a negative expected value play or fold his hand. Slow playing allows opponents to suck out on you.
Indeed, even when you are seemingly well ahead in a hand, slow playing on the flop can be dangerous, because it can revive a moribund hand and put it in a position to draw out on you. Again, you have 66 and the flop comes up Kc 7d 6s. Your opponent is holding JdTd. You slow play your set, Villain gets a free card, and the turn comes up Qd. Now Villain has an open ended straight draw and a flush draw, which he obtained for free on a hand you would have otherwise won had you not slow played.
On the other hand, if you really are way ahead, and the chances of a suckout are miniscule, slow playing isn't likely to hurt you in this way (though whether it will help you is dependent on the other two factors). The most obvious example is quads. This time, you have 66 and the flop comes up Ad 6d 6s. Now you aren't concerned about losing the hand-- the only scenarios under which you will lose would be if Villain holds AA and gets the case ace or holds Ax or a pocket pair of 7's or better and gets runner-runner. Straight flushes often meet the same criterion.
And while quads are an example of absolute hand strength justifying slow play, you can have the same thing occur with relative hand strength. Let's say that Villain is super-tight and only raises pre-flop with AA and KK, and he pre-flop raises and you call from the big blind with JT. Everyone else folds. The flop comes up Q-9-8 rainbow. Since you know Villain has an overpair, and is not going to beat your straight except with runner-runner cards, you can slow play if the conditions are right.
The advice I sometimes see-- "never slowplay anything less than a boat"-- is thus wrong. Whether you should slowplay depends on whether Villain has a serious chance to catch cards and beat you. That is based on your reads. If Villian has that serous chance, then you need to price out his draws. If Villain has little chance to do so, you can slowplay your made hand even if it isn't a full house or better.
Second, the Villain has to be more likely to fold than call or raise a bet. This is where slowplaying seriously goes awry in low stakes games. If your Villain is a calling station, why would you pass up an opportunity to get his money into the pot? And guess what? In low stakes games, many of your opponents are indeed calling stations. I've sat at tables and watched in disbelief as some player wins a 4xBB pot after flopping aces full or quads or a nut flush, all because the player was afraid that he wouldn't get any callers if he bet his hand, even though everyone has been calling everything down to the river for 30 minutes straight!
Indeed, if a low stakes player is not good at reads, I would recommend abandoning slow playing altogether. Sure, it will be frustrating if you hit a big hand and everyone folds to you immediately, but trust me, that doesn't happen as often as you think in low stakes poker. Until you are able to identify your Villains and determine how they will respond to aggression, you shouldn't be slowplaying. Indeed, there's also a psychological benefit to not slowplaying for the novice player-- it makes tilt-inducing bad runner-runner beats less likely.
Third, Villain is likely to bet in response to a check by Hero. This is less important than the other two factors, because if the Villain is likely to fold to Hero's bet and check to Hero's check, the reality is that Villain knows that Hero has him beat and you aren't going to be able to extract any value. Still, if you knew for a certainty that Villain will not bet if you check, wouldn't you go ahead and bet, because at least that gives you some chance of getting some of Villain's money into the pot? The point of factor 3 is to establish a presumption against slowplaying-- when you believe that you are equally unlikely to extract any of Villain's money by slowplay or aggression, go ahead and be aggressive and take down the pot, because that's the action that at least gives you a marginal chance of increasing the pot.
