It's an experience when you go up against an amatuer that has what it takes to be a pro. I did it once against a guy named Clarke Sowle in Dever, CO. I still remember it to this day. I'd lost fights before, but they were always fights. This was a beating, with no response. My instructor eventually had me bow out, and at that particular tournament everyone who faced him after me bowed out without fighting. Lucky me was just first.
He was just at a completely different level than I was, or anyone I'd ever even seen. He eventually went to Thailand to fight for money, and last I heard was money-making shootfighter in Japan.