Also i would like to add the point of how a buyer can choose what particular auction that they bid on, while sellers cannot control all of the potential bidders since you can only block old dead beats (yes steve, DEAD BEATS).
As a buyer, you can view a sellers feedback and get a good idea on how the seller operates. So if you bid, its your risk. I personally never bid on low feedback sellers; especially on big ticket items.
As a seller, I give all newbies a chance (they actually pay the fastest). I also try and weed out potential jack asses by viewing all of the bidders' feedback.