Rodeo roughstock live pretty pampered lives - although they are not stalled. I've never seen one that is too thin or not pretty well groomed. It it not unusual for the geldings to compete (yes, they compete) well into their 20's and better. They aren't over worked and they generally have very few joint/health problems. The mares may not compete quite so long - they are generally retired to broodmare status before they get to old for breeding.
I've seen some that were big babies when not in the arena - I even rode one on a trail ride and had a great time - but I nearly fell over backwards when I found out he was competing in a local rodeo the next weekend.
I've seen some that I wouldn't want to turn my back on, too - but they are the exception. Most may not be especially friendly (the one I rode couldn't have cared less) but they aren't vicious.