User blog comment:Neowitch/Villainous Working Girls/@comment-1595565-20120625000920

It's a psychological tactic if anything so the readers won't root for the villain. Most of the people who read one piece are male. Males think with their dicks most of the time, tending to favor hot women in the story regardless of where they stand. Oda is playing off that. By making ugly chick villains, the reader won't feel inclined to support any villains. Ask yourself this, who gave a better first impression when their characters were appeared in the story before you knew anything about them beyond their appearance, Big Mom or Boa Hancock? Question 2, what color Hancock's nails when she first appeared? Hot women make men feel more relaxed and trusting. Also, trick question, they weren't painted. Oda doesn't want us to feel comfortable around villains, that's why he makes the female villains ugly, and therefore more easily dislikeable.