We are never given specific details of how John's home looks, but we're given a description of how John sees it because of his unhappiness at home.
In John's eyes, the entire place is dirty and filthy. No amount of cleaning seems to help. He feels it can never get clean no matter how much they try to clean it. John feels this way because he his home is a place where his father mistreats him and everyone else in his family. Even their last name, Grimes, indicates filth and dirt.