Well, short of saying "I'm racist and that's why I hate Moira Stewart", I really don't think anyone is going to post anything in this thread that can literally be explained by "for no real reason at all" - obviously you have reasons for disliking/hating someone, but I think if the reason you dislike them doesn't justify how much you dislike them then that's what the thread's asking for...
I find David Mitchell annoying because lots of people think he's funny and put him on this comedy pedestal but whenever I've watched anything he's been in, I haven't even so much as smiled, and I think he has an annoying face. Completely irrational reasons to dislike him - he's just doing a job and appealing to a bunch of people, but he doesn't appeal to me.
IS THAT OKAY WITH YOU SHAUN!? HAVE I DONE ENOUGH!?!?!