What Do You Look For When Buying Used
 

What steps do you take when checking/diagnosing a used classic car through private sale (craisglist style)? Being that one typically can't do a full inspection like we'd all love to be able to do, what type of signs/problems do you look for while checking the car out?

My main concern is rust so I ask for a lot of undercarriage pictures, door jams, bottom/inside of doors and inside the trunk.

If the paint is nice I ask for pics of bodywork before paint.

Rust also is top of my list. When purchasing my Chevelle, which was 250 miles away, I asked the guy lots of rust related questions, concerning bodywork, because it had fresh paint. Of course he said it didn't have any. I made the trip expecting to find a little rust, in normal places, which of course it was worse than I expected, but not a deal breaker.
I carried with me a nice LED flashlight, and I crawled all over, and under the car. I crawled in the trunk, and looked up the B-pillars, which showed me rust under my rear window corners. I saw the floor pans needed attention, from crawling under the car. Take your time, and check it over well. You can't ask enough questions.

Good thread. Looking for a project car now. Excessive hidden rust is always a big concern. Bodywork can be an issue but can be worked out. Any other red flags to look for?