Roth infuses Donowitz with a savage glee that is sure to elicit cheers from audiences, particularly because he's on "our" side. You have to be a member of the Aryan Nation not to enjoy watching Nazis get what's coming to them. But having the vengeance delivered by the man who made torture porn a hot new movie genre adds a level of ambiguity to things. Are we cheering because we hate Nazis? Or because we like violence?
It doesn't seem as though Tarantino himself knows the answer. It's interesting to note that all of his films have explored vengeance of one kind or another, dancing around the notion of righteous wrath. In Inglorious Basterds, he unleashes hell on some most-deserving villains, only to turn things around and indict the audience for their own complicity in the culture of violence. It's a more-than-fair critique.