Suggestions do get better if you make an effort and use the thumbs to rate the TV shows. Don't wait for the Tivo to rate your shows for you (what you set to record automatically gets a
For those with a new TiVo without much recording history, you can get a head start by rating shows while browsing through the guide.
Also, even if you don't record suggestions, Tivo still keeps a list going. Make sure you go through that and thumbs down everything that is of no interest to you.