At the club where I play, the 3.0 team just had one of their players declared at 3.5, and all his matches were forfeited. The team went from 8-1 to 4-5, taking them out of the playoffs. The one loss he had came to a guy that was truly better than him. However, this guy didn't get bumped up.
My wife went to the 2.5 sectionals 2 years ago. In the first game of the first match, she put up a lob (not uncommon for 2.5s). Her opponent took a couple of quick steps back, sissor-kicked and hit an overhead that was good and bounced over the back fence. How many of you have seen a 2.5 woman do this? Of course, my wife lost, but felt lucky they won the 2, maybe 3 games they did win.