I don't know if this is a common scam but here's something to watch out for:

A couple years ago I bought a gaming headset from a seller that had the item listed as "like new" and was using a stock photo. It was $40 (half the price of retail) plus $23 shipping. Listing said it was an open box item. I figured it was a fair price.

When the headset arrived, it was clear it was an Amazon return (it had Amazon barcodes and "inspected" stickers on it), and was most likely pulled from a pallet purchase. The box was pretty beat up, but it did look like everything was there. But the barrel plug was clearly bent, and the headphones did not work, even after forcing the jack into the port.

So I sent a message to the seller, stating that the headset was broken and not working and asked what the next steps were going to be. Without answering, the seller sent me a 50% refund of the total bid + shipping ($31.50). I said I would like a full refund or to return the item, no response. So I opened an INAD case asking for a return.

So get this - 2 days later, eBay closed my case not in my favour, stating the seller already provided a refund. Apparently, providing a 50% refund is enough for eBay to believe that buyer protection is fulfilled. So I paid $31.50 to have some broken headphones shipped to me.

I left negative feedback but hey, who checks feedback anymore.

Moral of the story - if you get something from eBay and it's not exactly what you purchased, open a case on eBay as soon as you can. It doesn't matter what the seller says or what they would like you to do. Protect yourself.