fake ray ban sunglasses

i recently purchased a pair of ray ban sunglasses from a power seller on ebay, the seller claimed them to be authentic, when i received them the quailty was very poor, upon cleaning the lens the ray ban logo came off (not very good)why do these sellers get away with this counterfeit trading. idont know if i can name the power sell but what the hell i am going to anyway to prevent innocent ebayers being conned into believing they are bidding on genuine goods, the power seller is shop-mystery