It's been a long time since I've looked at it, but if I recall, the default is no rating (and doesn't count) until you actually rate it. If anyone happens to notice the next time they buy a track if it default to 5 starts let me know.
I also looked through the catalog at a few tracks that I know have been purchased and noticed that they did not have a rating. This would suggest everything is working properly, but again, if someone buys a track and sees it default to 5 stars, let me know.
Also, it could just be possible that the minusDrums tracks are just so good, that everyone rates them very high.

ken