I wish you had been more specific about what you wanted to talk about. What you wrote was not particularly clear. If you would like to be more specific now, I would be happy to engage in a discussion about fallacious arguments. What are "valid elements of a formal fallacy"? Indeed, what would a "valid element" be? What I originally wrote was that although, necessarily, all fallacies are fallacies, it is not true that all ad hominem
arguments are fallacious. That, of course, does not mean that ad hominem
fallacies have "valid elements" (whatever those might be).