It's funny, but you can also weed the morons out by not letting people spar until they have learned the basics of footwork and combinations.I've seen so many examples of people getting that wake up call since I started with martial arts.
Every semester we have at least one big, talky type that comes in all full of ego... only for the ego to get shattered once he gets manhandled by a software technician that weighs like 10-15kg less than him. It's very interesting to see who adapts to that experience and who drops out.
Every single overconfident moron type will just drop out just hearing that they have to do 5-10 sessions before light sparring, so you don't have to deal with them hurting themselves or others.