You can learn a lot about a seller by examining the seller's feedback page.
https://www.ebay.com/fdbk/feedback_profile/cellmatic?filter=feedback_page%3ARECEIVED_AS_SELLER&sort=...
Each feedback comment for selling is tied to a transaction, and unless the transaction was through a private listing, you can see the item title and price paid -- meaning that eBay actually collected a fee for that transaction, I believe.
While I have seen some very suspicious feedback comments for private listings of other sellers that indicated the possibility of a seller using "straw" purchases to leave phony feedback and pad the feedback statistics, such tactics for non-private listings of reasonably-valued items can get very expensive very quickly, and are generally not worth it to a scammer with a throw-away account. Keep in mind that eBay collects around 13% of what the buyer pays, so a few phony purchases of expensive items for feedback add up quickly.
