its a childish behavior dear
how can you judge a original auction sheet?
if he gives you car you will sign a paper n give to him , saying that you have check the car & paper up to your satisfaction level, and you will never be able to claim him.
so u don need the owner sitting in front of you,
his point can be, IF YOU GET SATIFIED WITH CAR, YOU CAN BUY OTHERWISE GO & CHECK OTHER CAR.