Every once in awhile I'll surf through the hidden comments to see what's been troll-rated. Recently, I've noticed that a number of long-time Kos posters have been getting troll rated for getting into fights with other posters over a personal conflict, or because they voiced an unpopular opinion (i.e, "people who think Kerry really won the election are wearing tin-foil hats").
My view is that such comments are not grounds for a 0 or 1. (Accordingly, I've been giving those comments 4's in order to balance things out for them.) Troll-rating, IMHO, should only be given to posts made for the purpose of disrupting the community. I'm certainly not hesitant to give out a "0" when I see a juvenile freeper type who is posting solely to provoke people and disrupt things. And you shouldn't be either. However, anything beyond that category (other than racist or similarly tasteless comments), doesn't deserve a troll rating.
Thus, I would recommend that, if you feel like giving someone a "0", look through the poster's past diaries and comments and see if they've been a serious person over time. If they have, perhaps consider giving them a "2" instead.