To be honest, I disagree - Even though I know where the ratings are, it's still difficult to locate. It's nearly impossible to see, and that's just bad design. Also, I was not aware that people actually rated tracks 0 stars. To me, seeing a track with 0.5 stars looks worse than one whose rating appears empty.
Anyways, if you make the player bar display empty ratings the same as zero ratings, I do not believe it would cause any confusion.
Firstly, there are two other areas to view a track's rating - the list view and now playing list - whose appearances I don't think need to be changed. And secondly, if it's bad enough to be rated zero stars, why would you be playing it in the first place?
Additionally, it doesn't appear to be possible to rate something zero stars in MMA. Unrated tracks look like zero stars, and the appearance does not change if I specifically set it to zero. (I don't think that's an issue however. I'm perfectly happy with that behavior.)