Does anyone know of any sci fi books with a similar story line to Wall-e or I Am Legend - where humans are forced to live in space and all that survives on earth is rubbish?
I Am Legend isn't about what you described. It is a short novel written by Richard Matheson about a survivor of a plague of bloodthirsty, animal-like vampires living in New York, and his desperate attempts to reverse the effects of the plague.
Just so you know, the book is very different from the movie. In my opinion, the book is far better (and the opinion of most people I know who have read the book and seen the movie).