I tend towards Positive Thinking, so I am quite happy selling & buying with Ebay since 1999. Turned over many thounsand Deutmarks and Euro, plus some Dollars and Pounds.
There were a few developments there meant as improvements, but you do not really have to use them. I never give feedbacks, unless somebody asks for. Waste of time.
Of course you meet complicated charakters or even idiots here and then, but that was only maybe 0,5 % in my case.
I think, Ebay is a good and comfortble place, to get rid of unwanted stuff or surplus material. For most goods there are people wanting it, so you can get a fair price. In some cases more than I paid for it. Most of the time, I ask for a minimum price. even if goods go away for little money, I know, there are at least two sides happy. Customer because he has the impression he made a bargain and of course me, because I got rid of the stuff.
Even PayPal makes sense for me. I gave up using a visa Card for international purchases. On the other hand, if I get my money a few seconds after the bids are over, I can start packing straight away. The alternative is going over to the bank to check.
In many cases, when I had the impression to know the customers interest, I offered them some more items privately. Worked most of the time.
It works even better, if people come around personally, to pick up their purchases. I always have some extra offers on the table.
So Ebay might be a strange place, but it depends on you, how to use it.