> Ad hominen is when you use an irrelavent insult in an argument
No, it’s when you argue the truth based on dismissing the speaker. So if Carl is an idiot, and Carl says cats are real, it would be ad hominem to say cat’s aren’t real because Carl said so. (Dismissing an argument isn’t ad hominemper se. Neither is name calling. It’s concluding based on not liking the speaker.)
Pointing out bias when debating an opinion hardly sounds ad-hominem, and in this case it looks more like OP's way to strengthen the veracity of the report while showing surprise rather than dismissal.
Is it still ad-hominem if you actually agree with Carl? Doesn't it make Carl's argument even stronger when you say "I'm always against Carl but this time he's right" which is the opposite of dismissing his idea, ad hominem or not?
> Is it still ad-hominem if you actually agree with Carl?
If you conclude X is right because Carl said so, it’s argument from authority.
> Doesn't it make Carl's argument even stronger when you say "I'm always against Carl but this time he's right" which is the opposite of dismissing his idea, ad hominem or not?
No. It makes his rhetoric (essentially an argument about an argument) stronger. But not argument per se.
No, it’s when you argue the truth based on dismissing the speaker. So if Carl is an idiot, and Carl says cats are real, it would be ad hominem to say cat’s aren’t real because Carl said so. (Dismissing an argument isn’t ad hominem per se. Neither is name calling. It’s concluding based on not liking the speaker.)