It's standard negotiation, you point out the flaws, damage, shortcomings to lower the price a bit. It doesn't work too well if you go overboard, if it's that bad why would you want it in the first place?
I tried to sell things on Craig's List. I had a $100 fax machine that I used maybe five times while selling a house. I was asking $25. Talked to a guy for half an hour about it and he still wasn't sure if it was exactly what he wanted. I donated it instead.
Tried to sell a Volvo, met some real kooks. I ended up listing it on a local Volvo site and I got two sane people who called me the first day, sold it to the first one. While the mechanic was looking over the car we compared Craig's List stories. It seems both sellers AND buyers are kooks. At the close of the sale I thanked her for not being insane.
Scott