There are a lot of posts here so this has probably already mentioned but:
What type of voting was it?
A show I was at this past Monday had similar results as you describe.
Reason: It was a popular vote, each entrant and viewer was able to vote for 10 vehicles. It's no surprise the largest car club present won all the trophies. They voted for each other.
Hard feelings? Not on my part. It was fun to hang out with my C5 buddies..... and I know inside (where it counts) that my car and a couple other C5s were much better than some of the "winners" (specifically that ugly ass pink cadillac with faded paint and dents).... ooops... I almost forgot I wasn't bitter...
Stick to shows that specifically have a "Modern Muscle" class that is judged by judges and not a popular vote.... then you stand a chance to win... if that is the reason you are at the show.
(I'm "in it to win it" but hey, some shows like the one on Monday is just one you have to relax and not worry about the win)