I think it a big part of it depends on the personality of the players. If a coach EVER needlessly demeaned or humiliated me, I would walk off of the field, period end of story. It doesn't serve any purpose except to make me lose respect for him or her and piss me off, and not in a good way.
I love having a coach who's willing to yell out comments to point out something I missed on the field so I could learn from it and move on. I also didn't mind having a coach with a throbbing temple during halftime who would occasionally curse and tell us we were playing like $h!t and that if we didn't get our butts in gear as a collective whole, we were in trouble during practice that week. It tended to work.
Some people need to be harassed or personally insulted to get by, some people don't mind it, and some people, like me, won't tolerate it. If you have to resort to being nasty to get the job done, then personally, I feel that you've got more problems than just your team. Yes, you sometimes have to put up with jerks in real life, but at some point you have to draw the line between being pushed or someone just being a hardass and someone who's personally attacking you.
