You know, I honestly couldn't list my most hated bands, I'd be here for an absolute age, racking my brains and cursing you for bringing it up.
I'll give you this much though - right now, if I could lock up any band and throw away the key (or swallow it for Tom and Jerry style comedic action), it'd be Scouting for Girls. They are the worst thing I have heard in a long, long time.
~ Adhamh.