It's also a foul to grab the cage, kick a guy in the balls, and gouge his eyes.
Are you going to predict it won't happen, that Bisping will "cleanly" beat Belfort.
Bisping can beat Belfort cleanly
But if we're gonna count people who mess up inside leg kicks, then there are a lot of fighters in the UFC that "can't win clean".
Fighters get caught out with the open-fingered gloves so much that I wouldn't call it fighting dirty...accidents happen.