As usual I understand what an ad hominem is far better than you do. You went for a shallow answerable than a deeper understanding. This source is better:
ad hominem fallacy - The Skeptic's Dictionary - Skepdic.com
"The ad hominem fallacy occurs when one asserts that somebody's claim is wrong because of something about the person making the claim. The ad hominem fallacy is often confused with the legitimate provision of evidence that a person is not to be trusted. Calling into question the reliability of a witness is relevant when the issue is whether to trust the witness. It is irrelevant, however, to call into question the reliability or morality or anything else about a person when the issue is whether that person's
reasons for making a claim are good enough reasons to support the claim."
I did not just call Bill an idiot. I also explained why that meant he could not be trusted. You conflated an ad hominem attack, which may or may not be justified, with an ad hominem fallacy.
Think of it this way, an ad hominem fallacy includes an attack that has nothing to do with the topic at hand. If I said that Bill is ugly, a true statement but still an ad hominem attack, therefore we should not believe him that would be an ad hominem fallacy, since looks have nothing to do with honesty. When I say that Bill is an idiot, a provable claim ( "tide goes in tide goes out") and he does not have a valid reason for his claims, or that Bill is a liar and degenerate (how many millions of dollars did his attacks on women that did not want to go to bed with him cost FOX?) and that he cannot be trusted, those are not ad hominem fallacies.
So wrong as usual, but a very good try. You are learning.