I have twice been scammed on ebay, once it was an ATU that the insides were swapped over and a claim it didnt work, so was a loss as i had no pictures of the insides. 2nd time was a tube Mic amp that clearly shows the tube glowing in the pictures but he still claimed back and ebay went with his side. It was working perfectly.
Electronics of any kind are really hard, I once sold a GFX card and marked it with UV pen. I had the buyer contact me saying it didnt work, I said well send it back but warned it was marked so make sure he sent back the correct card. he with drew claim and that was that.
Another was i sold a V7 radeon card with water block attached, with the original cooler, the buyer replaced the original cooler and knackerd the card some how, but ebay sided with me as he had removed the waterblock and card wasn't as sold.
I think Ebay is ok but you have to be real careful and list things as parts not working no returns, that way you are covered if the buyer try's to scam. Also explain why its listed that way to stop scammer's.