Being Obsessed With Punishing
Being obsessed with punishing overplays, perceived joseki deviations and non-standard moves in general is a bad habit. You may start underestimating your opponent, which is hurting your play and may result in embarassing losses even if you're the stronger player, both nominally and in reality.
Strong players may tell you a dozen of times (and they have done so on SL), but it is unlikely that you really grasp the meaning before you made the experience yourself. Then, you may come back to this page and leave a note here.
tapir: Today, as the crowning achievement of a series of losses, I played out a really self-hurting noseki sequence usually well-known to me while thinking I'm going to punish him. I even wondered about it for the whole game and only recognized when reviewing this game.