Actually, BDM it's impossible to give less than 1 star and it's also not possible to revoke them. When you first joined I gave you a 5, I guess others have disagreed since then.

If you are using firefox (other browsers might do it too) if you hover the mouse over your stars it will tell you how many people have rated you.

I use a binary system, posters either get a 5 or a 1.