My seller did the same with the 8/24 pins (from 2 auctions) that I found questionable. The problem is that when we send the pins back, the sellers can just send them on to someone else who doesn't know any better. Out of the 8, 4 of them looked ridiculously cheap. The others I felt were scrappers just by comparing them to other pins I had that were the same/similar.
Not to say I have a solution, I just felt that I was part of the problem when I returned the pins to the seller.
I went to DL last week and happily traded my pins that I felt comfortable with (even after working with my 2 sellers, I still had about 7 that I refused to trade). I found that of the ones I got in trade, about 5-6 of them *might* be scrappers. On the positive side, I trade for pins I like so I won't be trading them back anyway.
Make the return and feel better that you are doing your part. I just wish there was more we could do.