There are always stories that are known as being horrible, or as disastrous, and then, stories that were so awful to you that you had to stop watching, or came close to it.
What were the stories that weren't on that level, and maybe didn't do any serious damage to the show or to characters, but annoyed the hell out of you?
For me it would probably be Stacey Winthrop blackmailing Donna Love into giving up custody of her adopted son on AW. I hated the storyline, it just seemed overly depressing and unnecessary (this was used to break up Donna and her husband Michael when he learned later on that she'd given up custody to his biological parents because Stacey was blackmailing her over an affair she'd had that Michael didn't know about). Even worse, only Donna and her daughter Vicky held a grudge against Stacey - everyone else was fine with it...Michael even took her to bed.
I've always liked Hilary Edson but that story absolutely destroyed Stacey for me, and made me despise sanctimonious Michael to boot. Garbage.
The only good thing I can say is that I enjoyed the scenes where Vicky treated her like absolute crap, because Anne Heche never held back in moments like that. (my favorite was when she started spraying mustard on Stacey)