Rules to safer buying (especially when dealing with a stranger):

Never buy a car in primer.
Never buy a car with fresh paint, especially red.
Never buy a car without seeing it in good daylight.
Never buy a car that sags with the doors open.
Never buy a car that is rusted out in the door hinge pillars and windshield frame.
Never buy a car with water stains in the instrument cluster.
Never buy a car from someone selling it for a friend.
Never buy a car where the seller's name and current address is not on the title.
Never leave a deposit without a receipt detailing VIN and car description.
Never pay in full without a bill of sale and title and car in hand.
If you're an optimist, take along a friend who is a pessimist.

There are exceptions to every rule, but these will help keep casual buyers out of trouble.