Slow playing is an artistic concept in poker, one that requires a lot of timing, style, and the confluence of circumstance. Because slow playing, when done properly, can be so powerful and so profitable, it has ironically become one of the most overused techniques in poker among the new (and the bad) players. As a result of its overuse, it loses much of its ability to benefit.
Slow playing means to have the lead in a hand but act weak, encouraging other players to act strong or, in the case of a made but inferior hand, believe that they actually are strong. This entails, essentially, letting other players put money in the pot and just calling along, as if you were hoping to hit a drawing hand. The problems with slow playing, however, is that often you don’t get out of it what you want.
The goal of slow playing is to bet plenty of money for your monster hand by letting others lead at the pot. The problem is these others may not want to lead, whether because they have weak hands or they suspect you of skullduggery. Meanwhile every extra card that hits the table actually gives them the chance to beat you, which causes your trap to backfire, often in a nasty way.
If you start with pocket aces and check-call till the river, you are likely going to ignore the straight that has been materializing on the board, and push all in over an opponent’s raise in frustration. When your opponent calls and shows that he caught runner-runner straight to bust your aces, you only have yourself to blame.
Slow playing has its place and can, indeed, be a very powerful tool in poker, but its power—much like the bluff—lies in using it sparingly and in the right situations.