Ad Hominem is a personal attack on an opponent rather than an attack on their argument.
This informal fallacy is arguably one of the most prevalent bad arguments. It is used to discredit an opponent and distract from the subject of debate. It can imply an arguer’s position is irrelevant because of some personal flaw, or that their position is bias because of personal beliefs, or the potential for personal gain.
“My opponent argues that investing in little hats for animals doesn’t make sense. But, how can you trust someone who has such a poor history with his own personal finances?”
“Obviously you’d say that! You’re a bleeding heart liberal with no sense of practicality!”
“Of course library employees want more money for the local library system. It means they’ll have more room in their budget for raises.”