There are some exceptions. Orochimaru is one of them. Unless my memory fails me, at some point he simply started to get crooked with no specific reason. He was well respected in Konoha, and I don't think anybody caused him such harm that it would have pushed him to become the monster he did. He simply grew that way, being the snake he was. In time he did cause such grief to others, though, in the traditional ninja way.