There was a time, not long ago, when the heavyweight boxing champion of the world had a second, unofficial title: "The Baddest Man on the Planet." With all respect to Wladimir Klitschko, I think we may be entering an era when that title falls instead to the MMA heavyweight king.
That said, there are some fighters who are more deserving of the handle than others. Brock Lesnar, for instance, is a bad, bad man. He's the kind of fighter who scares other fighters. Big, strong, fast and mean as a snake, he punishes people for having the gall to step in the ring with him. Fedor may not be as nasty, but I suspect he's just as scary to stand across the ring from, given his history of dismantling opponents. In other weight classes, guys like Waderlei Silva, Anderson Silva, and BJ Penn have been getting in the heads of other fighters for years.
One could argue that simply stepping into a professional MMA fight makes a man pretty tough, but among fighters, only a handful seem to truly possess that aura of intimidation that affects how other fighters approach them. It is a hard thing to earn and a powerful psychological advantage for those who have it.
Which is all a really long way to get to my real point, which is that Chael Sonnen, is not, by MMA standards, a bad man. Nobody in the the UFC is afraid of Chael Sonnen. He may beat you, but the evidence suggests that he's not going to hurt you all that much in the process. When he made that ridiculous quote about how fighters behind the scenes defer to him over Anderson Silva, he was engaging in pure fantasy. If he wants to see someone who does scare people, he need look no further than his next opponent, but I suspect he knows that already, because I'm sure he's secretly terrified of what Anderson is going to do to his precious little brain.