[Zeke]

You can pull the plugs, turn it over with a wrench, remove the sump (if it's a 3.2) or the drain plug if it has one and look at the oil. You can look at the bottom for obvious signs of a pulled head stud and if it doesn't have the exhaust on it, you can see the ports for how it was running (beyond the plug check). Check the intakes with a flashlight with the butterflies open, if there's valve leakage in the intakes, it will show. I'd say you at least have get the thing up in the air to see this stuff.

You could go further and remove the valve covers since the motor is out. Lots of ways to size things up. I still wouldn't pay top dollar.