It's an old question, but this article has an interesting point, made in this paragraph:
And, even in literature, the view that highbrow fiction is somehow all broadly worthwhile does not long survive service on the jury of a book prize. Parcel after parcel arrives of books that somehow contrive to be both plotless and proseless, often involving near-escapes from sexual abuse on seaside holidays in childhood. Yet these works do not smear an entire type of fiction, in the way that [a certain best seller] does, for the simple reason that they remain largely unknown.
So, what the author is saying is that bad genre drags down good genre, but bad literary fiction can't drag down good literary fiction because no one reads it. I consider that an interesting point, and, in one sense, a feather in genre's cap.