As of right now I would say:

Pacman: The crazy, ignorant, racist, and least knowledgeable fans of the sport has made most boxing fans take a strong dislike for their hero.

Mayweather: Extremely talented boxer, but some just don't like him for his attitude, not to mentioned they feel he doesn't want to fight the best in his division and then there are the crazy Pacman fans that feels insecure that this guy is really the best p4p fighter out there and not their man.

Amir Khan: Some fans out there looked at his talent and was in awe until the glass chin was discovered to be his biggest weakness and feels he hasn't earned all his hype, especially the UK fans that are ticked off that their country is being conned by Khan.

David Haye: A blown up Cruiserweight that talks a lot of s-hit that hasn't done anything at the Heavyweight division. Some feels he just like another Khan but at the Heavyweight division

Antonio Margarito: Illegal Handwraps. Seen as a piece of trash now. Many fans wants him to be permanently banned from the sport.

Feel free to add yours.