In the case of a couple of the tshirts I have designed there are at the top two very poor reviews. These reviews have come from other tshirts completely unrelated to my design but yet these negative comments appear against my
One of the comments is "The printing job was very VERY disappointing. It looks like it's been smudged or something (NOT like the graphic that was provided)". If another designer loaded up a poor quality image and the customer purchased that I have absolutely no control over it. It would be like buying a packet of peanuts from Tesco, reviewing it merely saying "Stale and overly saltly" then that comment appearing against a packet of chocolate chip cookies.
The comments themselves appear to be filtered in some way by product keywords but since Zazzle have not decided to inform advise anyone how the comments appear against products no one can give a clear answer.
Whilst I appreciate that the system of having reviews against products should improves sales, in the short term the effect, and possibly the effect of a couple of hundred designers filling the blogosphere and twitter world with "Zazzle review system sucks" or similar will be negative for small time designers like me.