The Check-Behind Trap. (CBT)
I wanted to discuss what I'll call CBT w/o having searched around extensively, but from what I've found, I haven't seen this discussed a whole lot really while I use it effectively often. This is a variation of the usual situation in which you might check behind a player on the turn while you had continuation bet the flop with a mediocre hand and got called - planning to call a river bet and keep the pot small. There are of course several other spots..
The CBT is checking behind or in front of another player on the flop (or extended to even the turn in some specific cases) with a strong or mediocre hand intending to get more value from an either immediate bluff attempt (when out of position) or a later street bluff attempt (both in and out of position), or when someone connects with a worse hand they think is good in part because of your check. This is definitely most effective in heads up or sometimes 3 way confrontation's, and usually should be thrown out the window when facing any more players (or actually could be employed for different reasons [ie. pot control], although I'd usually bet out and take control in these more multiway spots).
As an example of a bit more borderline scenario you could do this in - Say your heads up with Q8 and the flop comes out Q-9-4 Rainbow and you are checked too. You could bet out and take the hand in position here or check behind aiming to create value later in the hand weighted against the additional small risk of your single opponent drawing out on you with a Kx, Ax, or even 8-10 type hand when a jack comes (Note: that this risk is heavily increased w/even one more player involved). Here, I argue that depending on the player's aggressivity and situation this will generally lead to more overall value than simply betting the flop in which case you will usually take it down there on the flop (the safer/secure standard route, but were considering overall value weighted against risk here.) Checking behind will often encourage additional action on the turn in which the opponent will either bet trying to steal the pot from you on a complete bluff, or may think his lower pair is now good. You can now call behind allowing him to bet the river, or raise it here. Generally, although very read dependant - I'd recommend the safer route of calling. If the opponent checks, you can now fire a bet on the turn, and they may call with Ace high or a low pair thinking your trying to take the pot. I will often do this with middle pair's even, and play defensively post flop just trying to maximize or squeeze additional value out of the hand.
Now for more optimal scenarios: This move is best applied when you have a Ax, or Kx and hit your top pair on the flop w/no overcards in the case of a king. Say you have 1 or 2 opponents before you. you either limped or raised with A4s, A5, A7.. Anything along those lines preflop and had two callers. Now the flop comes 2 T A rainbow. Both players check to you. If you feel confident in your reads check behind. If you bet - only players with an Ace, or that have you beat will generally call. Otherwise someone with something like K-10 may later lead into you on the the turn when a lower card then ten hits eliminating the Ace from his perceived range of your hands. There is a small danger of someone pulling out an inside straight (w/QJ, KJ, KQ) or two pair on you which is being measured against the value of you getting additional money in on later streets when someone try's to bluff at the pot, or thinks there mediocre hand is good. This may not seem worthwhile, but I promise with experience and being able to identify good spots it can be used quite valuably.
However, I think and have seen a number of times, while letting time dwindle down a bit like I'm thinking of the hand and then calling the turn - more aggressive players (in specifically 20$ or less SNG's or Tourney's) will often just push an absolute bluff on the river trying to take you off of a hand thinking your scared of the ace or thinking your just floating them since it was checked on the flop. Either way you can value bet the river if they check to you and maybe make an additional bit on both the turn and the river now whereas they would of just folded to your more standard C-Bet (continuation bet) on the flop. Against your tricky opponent, they may just check raise you all-in if they overthink the hand.
Does this work 'Out of Position?'
Yes - An example from a recent live tourney at the Bike's mini-series of poker deepstack event where I doubled up once and used two other times effectively:
First hand was with KK and preflop play was very standard against a poorer LAG (loose-aggressive player). I had seen this guy make a large raise twice so far the first 40 min in position after several limpers were in other hands bet and then bet aggressively when checked too. Preflop from the SB I reraised his 5x bb raise after one limper to 1500 from SB. (*MLT Tip: It's a good idea to note players styles that stick out as very aggressive or very tight as they often have a tendancy to assume other players are thinking and acting the same way as themselves when making moves. Before betting, raising, or checking against such a player - ask yourself what a bet, raise, or check coming from that player in your position would mean. Consider this prior to making the move and use it. ) The player pretty quickly called me in this case. The flop came out J 5 2 with two spades I believe. The only hand I'm really worried about here is JJ - but I'm definitely getting all my money in against this specific player minus the appearance of an Ace.
-- Here now I have two primary options; bet and protect my hand and probably take down the 3250 ish pot, or check behind. We still each have around 4k in chips behind and well 8250 just sounds a little more juicy too me than 3250.
I opt to check behind, but not only check behind - live - I reach for my chips kinda quick look up for a second and make a subtle smirk. I stop and sit and think for a little while (this is almost all act and based on particular players and my feel of their corresponding reads and views on me. Generally - try to have your whole hand planned out preflop - if the players bets/checks, etc, what will you do? but giving yourself time to make decisions is always wise when unsure. Think of how to maximize hand value) and finally check. He fairly quickly leads out for an almost pot sized bet of 2800 commiting almost 3/4's of his remaining stack. I didn't wait any longer and just moved in here at this point thinking he was commited and calling anything he made this bet with. He shows 88, and my Kings hold to take the 8350 ish pot. Admittedly, players this LAG-donkish (as not to be mistaken for a good LAG player) may call on the flop depending on bet size, acting, etc.. but it is much less likely in scenario's like this than simply checking to them...
Another hand was smaller but another example... I had flopped two pair in a 3 way pot and opted to check behind in last position. The turn goes player 1: check, player 2: bet pot, and I thought and called. First position folds. River is a blank and player 2 checks, and I decide to make a 1/3ish pot value bet as it now looks like he entirely bluffed the turn or is weak. He seemingly frustrated folds showing that it was a complete bluff on the turn and I collect what would of almost for sure have been double what I would have otherwise collected by betting the flop.
One warning: Keep in mind the added danger of potentially getting outdrawn on and use this move as a double edged sword, keeping a defensive stance, while maximizing value - not blindly pushing aggressively on the turn/river. Of course, with improved hands (two pair+;) consider raises, particularly on safer (non flushy/straight type boards). Consider ways to get max value by raising while putting your opponent on specific ranges and guesstimating what they'd call, or just pushing in spots where they lead into you and you have within 2.5-3x the total pot or less of your chips leftover with two pair (one being top pair on a non flushy/straight board). This will look like a bluff enough to a lot of opponents to get called just about as much as a normal value raise which actually looks stronger to a lot of players. (I'd say use this more in 30$ online or less, or 200$ live or less SNG/Tourney's while considering value raising more depending on your opponent in larger buy-ins) Once in a great while your opponent may have picked up a set here, but overall you will be yielding much more value from this play in the rare cases this happens.
This move can be used effectively in many situations - experiment with it a little if you haven't used it already. Let me know how it works for you.