Cracked.com, that oft-overlooked bastion of music journalism, has revealed its picks for the worst cover songs of all time. This is a topic that interests us greatly.20. "You Shook Me All Night Long" -- Celine Dion and Anastasia 19. "Downtown Train" -- Rod Stewart 18. "Knockin' on Heaven's Door" -- Guns N Roses 17. "Demolition Man" -- Manfred Mann 16. ...