Recently I started importing a large number of CDs into my iTunes library. I set up an “Unrated” playlist to play the songs/tracks that I hadn’t rated yet. As I was rating songs I noticed that some songs started disappearing from the playlist even though I hadn’t rated them yet. Googling this didn’t reveal anything useful other than that there was an album rating being applied to each track, and this was causing the songs to be removed from the playlist.