most fsbo's do not know the laws of selling a house like a sellers disclosure, they also usually sell for the market rates of others in the neighborhoods which isn't really fair since there are no commissions involved, they should really find out the market for their house and then deduct a 6% off the price and they put on market.
if you are considering buying a fsbo you might get an agent to help you, they can contact the fsbo and ask if they would pay them a 3% commission and aloow a one time showing agreement. you really need someone to help (work for you)
and if you don't get an agenet please insist on getting house inspected and ask them for a sellers disclosure.