I would say that I’ve only had a finite amount of bad experiences with ebay. Only one time the issue wasn’t resolved in my favor (I abandoned the issue). It wasn’t worth my time and looking back it was my fault anyway, “newbie” mistake.
I find that most sellers get angry when you tell them their description is wrong. Even when you provide links and proof they made a mistake it’s almost impossible for them to admit it or change their ad.
Regardless, I find eBay a good resource to fill in collection gaps. I do agree with Bob in the fact that there are better places to go but when you “need a copy” eBay works well, IMHO.