Ummm, maybe wrong, but I was under the impression that gold membership on alibaba is just a membership option for businesses to buy when joining.
If I am wrong, and it is a rating system of some kind, then no matter what colour they are, you would have to use your common sense if you are judging a high rating as indication that they are honest and only sell genuine licenced products, because no matter what rating they have, that isn't going to happen.