Sweeney Todd fans are notorious for causing these. Find any (and I mean any) song from the musical version on YouTube and scroll down. Lo and behold, there will be a gigantic flame war in the comments about which Sweeney sang it best. It's very easy for even the most peaceful fan to get sucked into the endless Cariou/Hearn/Depp battles, and God help you if you're a fan of the original penny dreadful or the BBC film version and dislike the Bond/Sondheim play. That's the only time the combatants unite.