Ebay is one of those things where you had better be handy if you want to use it. Sellers misrepresent condition a LOT. Unless it's unfixable junk, I rarely file a claim against a seller. I usually get very good deals, and expect to have to do some handy work. But, I DO make good use of their feedback system if an item is grossly misrepresented.
Case in point: I just received a knife sharpener for a friend who just started as a meat cutter at the local grocery store. He asked me to find him a sharpener like the one I had been using for him in my kitchen, and I did. It was a very good price, and included priority shipping. The seller had ~41000 transactions, and a 99.8% positive rating. It played out not well. First, the package arrived very quickly, but $13 postage due because there was no postage on the package at all. Told the PO to return to sender, and it was sent out again quickly. When it arrived the second time, I unpacked it and found that the unit was obviously dropped onto a hard floor from countertop height onto the foot recess, causing a large part of the bottom to be broken out and broke a part of the inside, which was rattling around. Every part of the unit was shown in the photographs EXCEPT the section which was broken, and the seller described the condition as "It is Used Condition showing some light normal use."
Because the price was so low after his shipping costs, and because I was able to verify that the unit was functional, I just got out the screwdriver and gorilla glue and went at it. I did, however, leave a neutral feedback, and noted the issues as accurately as possible in the limited space.
I almost never return items. A fixable item in the hand, at a very low price, is always better than nothing. The rest of the time, Paypal is usually very good. And when they aren't, I'll chalk it up to a "gambling" loss at the "ebay casino", and factor it against the times I've done better than most would imagine possible. But I still make sure to leave an honest, negative feedback.
Sellers and buyers alike are often guilty of bad behavior, and in my experience, the number of positive feedbacks provides minimal insurance that you won't get the pointy end of the stick. If more people used, and were honest in the feedback they leave, it would be a lot easier. But that gets manipulated as well, so it's not a great indicator.
Buyers and sellers alike should treat ebay as a casino. You can't win if you don't play, but if you don't have the stomach for losses, you probably shouldn't put your money on the table.