Well, Brando was Brando. He was the original playboy of his times. Fucked married women. Fathered numerous children from previous relationships. The list goes on and on. Enjoyed the hell out of it. He built that reputation since the beginning. I mean, forget George Clooney, Scott Baio(sorry), or any of those today male players that dated women back in the days. Those men would never ever come close to what Brando did or even dream of doing what he did. In Brando's case, once he saw something to screw around with, he did the deed and the job was done. And no one ever came close to his reputation at all in the 50s by far.
Sure, Brando had many faults and a very stormy relationship with his own children. But we can't deny his legendary status. Nobody ever came close to what he did. But I am rambling, so I'll stop.