Most of my clients are event planners of some kind. They tend to worry a lot that some little thing is going to bring all their tireless efforts to naught. When a celebrity is included, they'll often tell me to be very careful around the special person, because he or she is very touchy about photographs. In fact, I've never found the celebrity to be hard to shoot or work with.
Jay Cutler is a good example. The young lady directing me had so many details to control that I wouldn't be surprised if she took a week to relax after the Dos Equis promotion she organized. Jay Cutler, however, never even looked at me askance as I shot him, including as he failed at Jenga. The same can be said for Peyton Manning, Drew Breeze, and others accustomed to flashes in their faces.
I find that people at the top of their profession tend to have the personality to match. They're professional enough that, when being well paid to be nice, they tend to be nice. I showed this shot to Jay Cutler right after taking it and all he said was, "Oh. That's a good one."