In general I usually clap politely or nothing at all, only teams I generally have a desire to express my distain for are UW and USC, the other schools I just don't have the desire to hate. It usually just ends up being how I feel about that team, for instance I probably wouldn't clap Colorado since I really dislike Deion, but I really don't have any strong feelings against Cal or ASU.
OOC teams I generally clap politely, I can't really think of a team I hated that came here for a game I was in person for. BSU I probably won't clap for since I'm still pissed off at how they deliberately took out Masoli with a late head shot.
The games I really just shake my head at when I hear boos are when we're playing a team like Portland St. or New Mexico, I mean what is the point of that, they came here for a paycheck are completely overmatched and you're acting like this is some hated rival that just stole your girl, I mean come on!