Beating your opponent senseless when he's clearly not able to defend himself is dirty pool.

Frequently, MMA fighters go in for a kill shot when their opponent has obviously been knocked out.  If a fighter is knocked out and cannot defend himself, his opponent should use some discretion.  

If you have clearly won the fight and the referee can't jump in to stop the fight right away, you don't have to pummel the guy even more.  This only applies to fighters who have clearly, without question, knocked out their opponent.  Fighters should use some discretion in these instances when their opponent is disabled.