I was looking threw the Armory and had a look on many characters available for sell.
My question is : Why do they all miss a lot of equipment, and what's the point of buying a character that has 0 stuff ? (Considering it would be very difficult to play it, at first).
I am sure there is a logical answer, but I didnt find out :)
Character trading has minimum price that is based on characters gear. Removing a piece of equipment reduces that minimum price so the character can be sold at lower price. Because of how the system works, it's not really worth buying average items. In most cases people leave only a few BiS items on a character when selling it. That way buyer won't have to pay for items that will have to be replaced later or are easier to obtain.