I think it might be best to preface our judgements with an explanation for why we feel a comic is bad. For me, a webcomic is bad if I find it regularly and glaringly offensive, or simply not entertaining.
First one I'd list: Better Days (and the sequel comic). Naylor's Objectivist idealogy grates, but what made me give up in disgust wasn't even when Fisk blew up a building filled with mobsters and patrons and hookers to save the one girl he was there for (and who was therefore the only one that mattered). It was when his daughter's gym teacher told her that she was the only hope they had of doing well at the upcoming gymnastics event, because the others were hopeless. A teacher/student relationship is very simple. The student is required to follow instructions, and try their hardest. Then it's up to the teacher to make sure the student learns. If the kids are trying and not learning, it's the gym teacher's fault; the "my child is inherantly superior because of genetics" really rubbed me raw. (and I speak as an instructor)
Second is one I'm shocked no one has mentioned yet: Least I Could Do, by the same author/artist responsible for Looking For Group. That's mainly because protagonist Raine is an overgrown, immature, criminally irresponsible manchild who regularly endangers everyone around him while having lots of sex (apparently due to possessing an oversized set of genitals). I gave up on that one after the thread in which Rayne is kissed and thanked by his friend's wife after Rayne bulldozes their way out of a cabin in a winter blizzard so she can give birth in a hospital. She had somehow conveniently forgotten that Rayne was the reason they were there in the first place, in the hopes of recreating the events of Evil Dead and having fun killing zombies with a chainsaw.
Third would be Black Tapestries. Simply because it was so... repellent. None of the characters were sympathetic, everything was vile and sucky. I read through the sum archive at that time and then quit in disgust.
I should note that whenever I dislike a webcomic, my response is to... stop reading it. I would offer my admiration for those here who share my feelings and simply refrain from reading the comics they dislike. I say that because Naylor in particular has a "hatedom" of people who obsessively view everything he posts so they can complain about it. If you dislike something, then ignore it and find something you do like. After all, there's a huge variety of webcomics out there... and if you don't like webcomics, there are plenty of other things to entertain as well.
