B&A: Should books have Ratings like movies or TV shows?

In a way, there sort of already is a rating system, isn't there? Books are categorized into Children's, Young Adult, and then just plain Adult. I'm sure you wouldn't find the book that you picked up in the Children's or YA sections (unless it was put there by accident). And I actually don't think that even *those* "ratings" should exist. It limits the books, and especially people's perceptions of the book. But anyway, an even more detailed rating system such as the one you're describing could be beneficial, but somehow I feel like it would "de-class" literature. You know? Bring it all down to the level of pop-culture, with movies and video games. (And even then, there are definitely lots of movies out there which are absolutely pieces of art.) I probably sound like a snob, and I definitely see the benefits of rating maturity content in literature, but it could get really tricky. Sexual innuendos are implied in so many different ways in literature without it being explicitly stated. How would you rate a novel or book of short stories like that?