It doesn’t matter to that she can’t hold the tune, or gets the words wrong.   The joy that overcomes her is worth her having no shot at American Idol.   Sometimes   her singing is soulful like Sarah   McLachlan , sometimes she rocks like Sheryl Crow,   sometimes she morphs from moment to moment like Nelly Furtado, most times its buoyant like Gwen Stefani.   She can be a temperamental diva, but it always makes for a good show.