Any list that doesn't start with Emma Stone in La La Land is void. It would be well beyond the Geneva convention to subject even the worst terrorists to her "singing" performance in that film. (Although it probably would make them "sing"--so to speak)And Brando wasn't nearly that terrible in Guys & Dolls. In fact I think he was fine. And it takes guts for a non-singer to sing in the same movie with Sinatra.