I get a few. The mean spirited ones, I just deny and then delete forever. Overkill huh? They say that any comment is good because it shows that..
1) the viewer must have read our hub - we earn from impressions, so it's a win.
2) the viewer took time to say "This is a piece of chit!" or something to that effect - comments, even negative chitty ones, give our hubs a little boost. Comments whether we like it or not, update our hubs as far as seach bots are concerned.
So, if it is an old forgotten hub, and if the comment is not too mean, I just let it go. Free update for my hub. I win!