Most classic fallacies are arguments which can be easily and accidently extended beyond their area of applicability. So they should be used with caution.

For example, if I'm arguing with you not to trust someone's research paper, ad hominem could be applicable, if I mention previous fraudulent papers, less so the moral stance of the researcher on spousal fidelity.

The point is labeling an argument a fallacy puts that cognitive warning sign on it, which demands that you you go the extra mile and show why this argument is valid in this case. If you fail to do so, you are asking those who don't currently agree with you to bear the entire burden of proof to substantiate that you are not simply committing a fallacy. Which is at best naive, at worst self-sabotage.