Rhetoric surrounding allegedly "bad" films seems to take on an air of collective agreement, even objectivity, more than discussions of "good" ones. For instance, everyone knows that Ed Wood was named "the worst director of all time," yet there's never any follow-up discussion of in what terms?, or says who? (It was Michael Medved who made this claim; older folks will recall he was co-host of Sneak Previews, he's now a right-wing political commentator and author).
My favorite online film writer, Vern, has an essay on Nerve.com about the "Razzie Awards," and why they should offend the sensibilities of people who care about movies. His feeling is that we should be just as skeptical when undeserving films get labeled as "worst" as we are when undeserving films get named "best" (i.e., Shakespeare In Love, Crash (2004)). It's a short essay, and entertaining; I recommend it highly.
The story is here.