Although if you know how to run reports, it's not really anonymous and sellers are able to identify who dinged their stars, but now, apparently, that will be changing too.
http://announcements.ebay.com/2014/...service-you-expect/?_trksid=p3984.m2301.l3955
http://announcements.ebay.com/2014/...service-you-expect/?_trksid=p3984.m2301.l3955