I agree tampering yes, fixing no. I mean didn' Stephen Garcia get kicked off South Carolina for potential point shaving? That's a pretty serious tampering allegation whether its true or not.
I also believe in college coaches know what the spreads are and if its possible for something unlikely to happen (like South Carolina's safety to end the game vs Miss State and get the cover) then it will happen as it doesn't affect the win/loss outcome, only the cover/non cover outcome. I don't put anything passed anyone when it comes to sports betting.