Exploitative play
From PokerAI
Exploitative play is the practice of taking advantage of an opponent's weaknesses in a game. Since, for example in poker, most players do not use Nash equilibrium strategies, the most profitable counter-play is typically also not a Nash equilibrium strategy. As a consequence the most profitable players (human or AI) will be ones that efficiently take advantage of the other players' weaknesses.
In fact, the usual notion of poker is that there are fishes (who play weakly) and sharks (who play exploitative).
Another familiar example of exploitative play is the use of tells in poker.
For computer players, exploitative play can range from simple rules-based notions to sophisticated opponent modeling. The University of Alberta games group has published some rather interesting reading on opponent modeling in heads-up limit hold-em.

