No limit Texas Hold’em is an aggressive game where players make lots of bluffs on the flop. Most hands that are played are heads-up or three handed by the time the flop hits the table, so most players in late positions, or the pre-flop aggressors, will make a bet into a flop if no one else has. Most half-decent players understand how important it is to make continuation bets in an attempt to pick up a pot where no one has hit the flop. With so many players playing like this, it can be profitable to stay in hands against the right kind of opponents to counter this strategy.
If you’re in a hand and a late-position player, or the pre-flop aggressor, makes a bet after the flop comes, it can sometimes be a good play to see if that opponent will bet at the pot again on the turn if you call their flop bet. If they think you are trapping them and orphan the pot by checking the action to you on the turn, you can put in a bet to represent a made hand. If they missed the board, which will happen often, you can pick up an easy pot without having to risk a lot of your chips.
One always runs the risk of being wrong and calling down bets from an opponent with a good hand. You should find that out on the turn, and you should be choosy when you decide to attempt this play. Try to limit it against players that you know will put down a missed hand with over cards, and look for situations where the continuation bet does not fit into a value bet amount for the pot involved.