Well, lots of people shop at Ebay so that's a positive. People have also already heard of it, so they trust it too.
money can be made via the affiliate program. My only gripe is the algo they use for payment.. seems very inconsistent but they pay and have paid for years..
Any affiliate program relies on your ability to send targeted traffic. If you have a blog with hot items posted with links to ebay you can be successful. Lots of ways to make money with ebay including as an affiliate!
Through affiliate program you can make money, for example if you are a seller you can make money by sending traffic to their own listings as well as to other seller's listings, you can earn commission on each purchase.