The Horror of a Horror Series

Why horror series just don't work with a little fun poked at Anne Rice.

Shlocky series are the rule in all genres, right? It's not like horror is filled with titles like L is for Lycanthropy or The Cat Who Was Possessed by a Demon and Ate My Child. But while mystery might be filled with series that gradually decline (Janet Evanovich comes to mind), it's practically defined by authors like Raymond Chandler, Arthur Conan Doyle, and Erle Stanley Gardner, all of whom paved the way for authors like Walter Mosley, Tony Hillerman, and Andrew Vachss. Over on the science fiction side, authors like Lois McMaster Bujold and Kage Baker have only gotten better with time, and fantasy, of course, has its roots firmly planted in Tolkein's original trilogy (currently expanded to about seventy books courtesy of son/literary whore Christopher). So if the other genres can manage A-list series, why can't horror?