When I was in 11th grade, or thereabouts, our school library started a "Middle School" section with books geared towards pupils in grades 6–8. (Up till then, there had only been "Junior" (K-5) and "Senior" (6-12) sections.)
Those books included the Sweet Valley High series of books. For a lark, I started checking those out and reading them.
By the time I got to book 5 or 6, the librarian (who knew me fairly well; I spent a lot of time in the library) asked me not to read them any more :) I think it was something about "can't you read anything better? That's not really appropriate for someone like you", or along those lines.
I thought it was funny; I considered my reading them a kind of meta-joke, given the intended readership. I did quit after book 15 or so, though.