This happens more than you think with older cars sold by non-car people. I bought a vintage Porsche 914 from an estate sale. The photos were dark and dusty. The listing said: "Old car, sat in garage for 10 years, doesn't start."
I towed it home, put fresh gas and a battery in it, and it fired up immediately. Then I started digging through the service records in the glovebox. The previous owner had spent a fortune on it before he got sick—fully restored suspension, stainless steel brake lines, and a recent professional respray in the original color.
The family just wanted it gone. I ended up with a $30,000 car for about $6,000.