I would try to buy the car at a in person auction - for sure if the residue isn't something bad.
However, at this particular online auction I would not even try it. Why? They showed a Utah inspection sticker from 1985 on the windshield. That's almost 30 years ago and could be the last time the car was on the streets. Combine that with the unknown residue on the car, I think it isn't that great of a deal. Big unrepairable problems can be found on a car that has been in storage for 30 years. Did you notice there wasn't any pictures of the interior?
Sometimes the detail of the pictures is a good thing or bad. Depends on how you are looking at it.
But you can get a crate motor next to nothing and corvette central and ecklers has all stuff corvette stuff reason I know this is I'm a corvette owner. If a person can get is vette for 3,800 a guy could make some money. But you are correct the picture dont show inside but do show speedometer and to me they are hiding something and when I called they would not answer about the interior. Still a good find thou