Ah, so a precrime thoughtcrime ad hominem? :-D
No. A bias you haven't noticed in the formation of your opinions of an argument is, however, an ad-hominem. Thoughtcrime is the refusal to think certain classes of thoughts; it's more useful to be able to analyze your own thoughts for faulty patterns, so that you can correct for them, than pretend they don't exist.
I have a feeling you're extending the definition of ad hominem into places it wasn't meant to go. It is, basically, an invalid method of refuting an argument. It says nothing about which arguments to pay attention to, for example. Calling even a "useful" ad hominem something like considering the reputation of a speaker before deciding whether to allocate your valuable attention to his speech is a stretch, I think.
Say what you mean. You disagree with my definition.
It's not a stretch, however. You can ad-hominem in your mind - if you think the words "This person is an [x], so I don't have to listen to them" as a reason for ignoring an argument you should be listening to. The failure to express this thought, but acting as if you have, is no less the same class of problematic behavior - more so, for your refusal to acknowledge the reason for your dismissal.
No.
That wasn't an entirely serious sentence :-)
You can ad-hominem in your mind - if you think the words "This person is an [x], so I don't have to listen to them" as a reason for ignoring an argument you should be listening to.
I certainly do that -- it's just that I don't think this activity can be usefully labeled "ad hominem". There is a tricky part in your sentence, though -- what is that "should be listening to" and where does it come from? How do I know what I should be listening to?
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.