In a sport such as prizefighting, personalities sell tickets. So controversy, within reason, is a good thing.
Floyd Mayweather generates nearly as much revenue from people who want to see him lose as he does from fans who love him.
When Muhammad Ali faced Joe Frazier the first time, they billed it as "The Fight of the Century." The way that fight's narratives blended with the great political controversies of the day was a major driver for making it so huge.
When controversy goes too far, it can risk turning off fans or even making the sport less legitimate. But it's a fine line promoters are generally willing to tread.
Here we take a look at 10 of boxing's most controversial fighters.