> Tu quoque (Latin for "you also"), or the appeal to hypocrisy, is a fallacy that intends to discredit the opponent's argument by asserting the opponent's failure to act consistently in accordance with its conclusion(s).

As the old saying goes, even a stopped clock is right twice a day.

I say people should get some exercise every day. In practice, however, I only get to the gym once or twice a week. That means I'm a hypocrite (and a lazy one at that), but it doesn't mean people shouldn't get some exercise every day.

But even if I accepted that pointing out hypocrisy is purely argument by ad hominem, I don't see how it would be irrelevant. If someone believes something radically different from me and therefore works towards radically different outcomes, I consciously try to stay open minded in case they know something I don't. If someone isn't consistent in what they profess and what they work towards, I don't feel I owe them that sort of hearing. At best, their ideas are good but they don't understand them well enough to represent them. Would you really call that unfair?