I don't mean the ones who are supposed to be the obvious villains, more the ones who do something exasperating or those who do something generally shit when you thought they were ok.
For example, I'm on holiday at the moment reading Tess of the D'urbervilles (as I've never read it, saw it in the library and thought I'd give it a whirl). Angel Clare has just done something to make me say "oh you complete shit" out loud.
The guy in the next tent was a bit startled.