Disney's frightening children's band The Doodlebops seem to be mistagged slightly...with tags like "approximately 1000 times less pleasant than extreme anal caving" (which may be true if I understood what 'anal caving' meant), and "everytime you listen to this crap a truck hits a granny" (which I'm certain could not be true.)
Similarly, Kidz Bob is the only artist tagged with "mistimed on the chainsaw juggling routine and became an instant eunuch"
And while I haven't heard any of Raffi's recent albums, I seriously doubt he's changed his musical style enough to be considered brutal death metal.
Other tags that I've been amused by include
i am more emo than your mom
and this one, which I actually used as a tag before I realized it'd show up in my profile forevermore:
songs that make me cream my panties