Which is why I didn't suggest a delineation based on manners. An ad hom is a logical flaw in an argument. Manners<>rudeness is a continuum, requiring an arbitrary judgement. Calling out ad homs is much more black and white. It also happens to cut out a fair amount of rudeness - just not all. An ad hom doesn't even have to be rude. As one immediate example, Jan Ardena habitually dismisses logical arguments by pointing out that they are coming from an atheist. It's not rude, it's not even false, but it is a fallacy.