I've actually had this happen to me. I had a few of the judges outright give me 3rd for the performance I did, and others just disqualify me. It was a closed syllabus event and we danced for the crowd... messed around with my pro on our cha cha routine.
It was fun, but I wasn't terribly happy after I found out you don't automatically get first place.
It was still worth it. :)