rate books?

I have come to a cross roads in my life. A place where I choose all sorts types of books, from the intriguing fiction to a biography and my favorite are the ones that study out human nature and our emotions. But I am tired of getting cozy to read what I think is a great book only to be shocked by language or explicit scenes. I don't want to skip entire paragraphs or pages to enjoy a story line. Most often it happens Just as I am entrenched in the story and 200 pages into the book..its is so frustrating that I am left to wonder if I am sinning by the continuation of reading or if I am being ridiculous in my expectations that there can be a book written in recent years ( other then twilight) that is clean. So I ask all of you...is there any kind of web site where books are rated?? I mean Like my favorite web site www.kidsinmind.com which tells you whats in each movie. If not prehaps I have just found my new life calling becuase I think we should have ratings on every cover of a book before you open it just so we know what your getting into. we don't sit down to a movie with out knowing this why do I want to read and fill my mind with unclean words? I am excited to hear feed back.