Towards a general theory of movie suckitude

The Daily Beast (for which I occasionally blog) goes the love-him-or-hate-him-at-least-we're-talking-about-him route, in order to quell the debate over Tarantino's Inglorious Basterds. I have a question: how come, when people always make this argument, they're always talking about bad movies, never good ones? This is not to say that controversies don't sometimes erupt over good movies, particularly if the subject matter or theme is charged, but when the controversy centres over the quality of the movie, the movie generally sucks. JFK, Basic Instinct, Natural Born Killers, Crash, Inglorious Basterds. I cannot think of a single example that defies this rule.