Because Cutler is white clear and simple, a black guy is always the hard sell. It's not racist it's simply because people gravitate to people that look like them. Cutler knew this is why he got chosen as he looks like the all american ideal, half the reason he had the stupid ass hair cut was because it made him look cool to the punk kids in highschool.
In bodybuilding or in general?
If in general it's irrelevant - Michael Jordan, Tiger Woods, Shaquille O'Neal etc etc...
And even in bodybuilding, Ronnie and Lee Haney tried to market themselves as best they could but always fell short because bodybuilding is an underground subculture, not a proper spotr, so they could only take it so far.