eBay has been my main buying site ever since Amazon was delivering fake stuff to me. Stuff advertised as 3M would be a Chinese fake. Between audio stuff and even hockey pucks, Amazon is awful, but eBay has been perfect for me. Never an issue, now I will be knocking on wood while putting a horseshoe on and eating a 4 leaf clover.
I've heard of that issue with Amazon but haven't experienced it myself. At least their return policy is good.
My issues with Ebay usually wasn't the buyer/seller, it was Ebay itself. They're garbage IMO. As a buyer it's ok, as long as you do your due diligence and check the seller out real good. As a seller it's a nightmare. I'd rather just throw my stuff in the trash.