Every once in awhile when you’re playing live poker someone turns his hand face up in the middle of a hand. These situations can be tricky to play, because a lot of what you know about poker goes out the window. Poker is a game of incomplete information. Uncertainty borders every decision you make. Take away that uncertainty and you’re playing a completely different game. Fortunately the new game, in which you have perfect information but your opponent is still in the dark, favors you immensely.
First a bit of math: according to The Mathematics of Poker, in a one street game with omniscience (that is, you know for sure whether or not you have the best hand), the optimal bet sizing with your entire range is to go all-in, regardless of the size of the pot. I don’t really understand why this is the case, but I’ll take their word for it. So if your opponent turns over his hand on the river and you decide to bet you should go all-in. That’s what the math says, anyway. As always you may find it preferable to play an exploitative, rather than game theory optimal, strategy.
If he turns over his hand before the river I think it makes sense to bet small. Your information advantage is best leveraged over multiple streets. Even if he thinks he has the best hand on the flop, calling is still dicey because he’ll have to play two more streets on which you have perfect information.
So: if he turns over his hand early on, bet small to leverage your information advantage. If he does it on the river, strongly consider going all-in even if the pot is small. That’s the sizing part, but how often should you bet?
There are basically two kinds of players: those who will turn over their hand and fold, and those who will turn over their hand and call. I don’t think there’s much in-between. If you see someone turn over his hand and face a bet, make a mental note of what he does next. He’ll likely do the same thing every time this situation comes up.
If you’ve never seen someone do this before, you have to try to guess what kind of player he is. As a pure numbers game, I think there are more turn-over-folders than turn-over-callers. It would seem to go against human nature to bet when you know your opponent has the best hand. Accordingly, bets in this situation tend to get a lot of respect. Some players seem to think that exposing their hand gives them a sort of insurance against being bluffed, so when they do face a bet, they think they can safely fold.
That’s not to say the callers aren’t out there. The most important question to ask yourself is, is your opponent a believer? Does he tend to give opponents credit for the hand they are representing, or is he constantly suspicious? If he’s a believer he’ll almost certainly fold. If he’s not, he’ll probably call. A player who is insecure or ego-driven is particularly likely to call just to prove the point that he can’t be pushed around. Fortunately, belief or disbelief manifest themselves in a variety of poker situations, and they tend to be fairly consistent throughout someone’s game. If you’ve been paying attention you should have a pretty good idea what kind of player you’re up against.
My final advice is, if your opponent turns his hand face up and you can’t win at showdown, when in doubt, bluff. In practice I rarely see someone call in this situation.