...the paint on that looks pretty good to me. I think the odds are pretty good what you're seeing is some corrosion between the paint and the exterior surface of the top tube. The Casati I bought was a total strip and repaint job (that I took on, myself), so I can't give you a real good idea about current value. It ought to be worth about the same as any similarly equipped Italian bike with a frame from a small production shop.
There's someone selling off a stash of NOS frames here:
https://www.adrenalinebikes.com/stor...oductid=126091
Casati is still in business, and producing frames.