Originally Posted by Gozarian

Calling someone a hypocrite is almost always an ad hominem fallacy. It is also specifically referred to as an ad hominem tu quoque. It is deceiving and misleading. For example, if DWB claims that smoking cigarettes is wrong, and Gozarian tries to rebut it by accusing DWB of smoking cigarettes, Gozarian has made an ad hominem tu quoque fallacy. The fact that DWB smokes cigarettes does not disprove the claim that smoking cigarettes is wrong.