Typically slow playing in poker is a bad idea but there are some circumstances that warrant it. Many players slowplay automatically whenever they have a strong hand like three of a kind but this is a foolish poker strategy. In order for slowplaying to be profitable, the pot must be small, the board should not have many draws on it and your opponent must be able to draw to a second best hand but not be likely to outdraw you. With all these conditions you can see why it's seldom profitable to slowplay! None the less, it remains an extremely popular tactic, undoubtedly because of the thrill people get from being "tricky".
The most common example of a hand that is usually a good one to slow play is top set on a drawless board. Since you have top pair twice it's unlikely anyone has it even once, so it can be profitable to allow them to pick up two pair or to hit a top pair. While an observant player may well figure out what you're up to when you raise preflop, check the flop but then bet, raise and go all in on a seemingly innocent turn card some players simply cannot see behind some arbitrary level, such as top pair or two pair and you can profit off their inability to properly assess the situation.
One of the many dangers of slowplaying is that since your hand is so powerful you are more than likely going to lose a lot of money if you lose with it (indeed, as the saying goes if you don't lose a lot of money when you lose with a set, you're probably not playing it correctly); you offer your opponents infinite odds to draw out when you check. None the less, this move does have it's time and place and while I have been known to lead out with flopped full houses, I won't look down on you if you don't.