A nice 'idiot'. To be more specific: I feel that 'idiot' is a bit rude as a term to address someone, so even if the person I interact with isn't smart, that doesn't automatically mean he/she is stupid.
I have no experience with working with assholes (had plenty of asshole teachers and classmates in school though), but I do know what that means thanks to my parents, and I sure as hell would prefer a nice but a bit stupid person instead of a smart SOB - intelligence isn't an excuse to be rude to anyone.
By the way, no one says that a smart person can't be polite as well, nor a dumb person can't be a jerk.