Here is what I do.
I am an ebay seller. The vast majority of my feedback posts from my buyers include lines to the effect of "Top quality chip", "Chip arrived as described", etc.
If I was looking to buy a chip on ebay, not only would I be looking for positive feedback, I would be looking for "specific" feedback comments that refer to the "quality" of the chip and whether it "arrived as described". Alot of the ebay buyers are not as particular as we are when it comes to the condition of the used chip. Many of them are happy with just a "used" or "circulated" description in the actual auction. If you want to see what I am referring to, pull up and read my feedback on ebay. I am "Rainbowlightart" on ebay. Hope this helps!