MJ wasn't even much of a bad girl while Gwen was alive. I can't disagree with what Romita said about preferring Gwen for Peter because she was more "ladylike," but that's because MJ was flighty and somewhat superficial at the time, not because she was a whore.
One of the reasons that Stan Lee's stories hold up is because he seemed to like his characters and he tried to make them look good. That includes MJ.
Come to think of it, he was the first one to marry Peter and Mary Jane. He can't have thought it was too bad of an idea. But I guess those professionals understood Spider-Man and MJ better than the man who created them did.