I know who the worst commenter is. However, he's also a decent contributor once in awhile. Knowledgeable on many topics, but sometimes condescending and crass. He has been around forever, which seems to make his comment-tenure here a bit questionable. Legacy users get preferential treatment, but where is the line?
I am guilty of looking away as well, for the reason stated above and due to my own personal rationale. I will not name the commenter (he'd screech bias anyway), but the people who've been around this site for a bit know who I speak of - as do most editors.