Here is a terrific piece in the New Yorker on Why Do Americans Believe in Muslim Rage? A great quote:
Some of the protests appear to have been organized by fringe political parties and radical activists; for them, “Death to America” is a mobilizing strategy. The rioting they encourage is about Muslim rage only in a tautological sense: raging Muslims do the burning and looting, but they do not typically attract even a large minority of the local faithful. The faces on American screens are often shock troops, comparable to Europe’s skinheads or anarchists.