Let me give just one example:
Shiloe Steinmetz. Won the NGA Pro Natural Olympus in 2003. Entered the WNBF Pro Natural America in 2004. Also entered the NPC Junior Nationals and IFBB North American in 2004. Most recently won the heavyweight class of Team Universe in 2007 and came in 15 in the World Amateur Championship.
however I think the real reason for the IFBB Pro League warning is that on the poster hanging at Gold's Venice advertising this contest in Las Vegas it implies that some IFBB pros will be guest posing or otherwise in attendance. The IFBB is now saying that pros cannot because the contest is not a sanctioned event.
But back in November I attended Coloso in Mexico City, a non-sanctioned contest held the exact same day as the IFBB Mexican Championships (that was the IFBB's choice, as Coloso has been held at that time for a dozen or so years). Coloso had an IFBB pro, Gustavo Badell, in attendance, signing autographs, handing out a couple of trophies. He was even used in the advertisements for the contest. (I remember he was also on an oxygen tank most of the time I saw him. sure it's 7000 feet, but come on. he's suppose to be an athlete.)
if this is really an IFBB rule, then once again, they only enforce it when it's convenient.