One of the not-so-fun things in the world is to get insulted or, in the words of Kelso from That 70's Show, get "burned." Now, let's imagine what it would be like to be insulted by some musician on one of their albums -- that "burn" I can only imagine was magnified by a million.
Nevertheless, some of the greatest insults come from music. I personally wonder if those who inspired these songs feel sorry for what they did -- depending on who they are, that is. We will probably never know the answer to that one.