From my frequenting the local watering holes, I've seen that 90% of what makes a good bouncer is how he carries himself. I've seen huge bouncers (6'5", 300 lbs of muscle) get picked on, while some tiny bouncer (5'6") rules the roost, because the huge guy was too quiet and reserved, while the tiny dude let everyone know he meant business. He just had that air about him that you don't fuck with him, while the other guy just seemed like a big dumb jock.