An ass is an ass whether on a road bike, mountain bike, skis, bobsled or whatever. I've met some great mtbr's and roadies and to try and generalize one group as being better behaved than the other is misguided. In fact, the biggest ass on any bike that I have ever met was on a mountain bike in the DuPont State Forest in North Carolina. He almost went back to the trail head without his teeth if his girlfriend wasn't there to smooth the situation over.