I've gotta say I never really participated in any hunting contests other than here on HNI. I'd love to do a groundhog contest though, next to turkeys and deer I really enjoy shooting these things.
I've seen some really crazy stuff though in 3D. Guys that average 5-10 points below the top scores somehow getting on a 3D course alone with no one in their group and magically shooting their highest score of the year and winning. I also saw one group of archers last year (all buddies) and one of them was actually a really good shooter. He would always shoot first in the group, and as it turns out was using aluminock. Everyone in his group now had a great aiming reference.

The thing with 3D, is that you gotta be willing to call people out, and shoot in peer groups score wise.......that really helps to keep things honest when you don't have buds scoring each others arrows.