I'm considering buying a car that was recently re-painted with spray paint. I'm unsure why the owner used spray paint to paint the car. This vehicle would be something I would restore slowly over time but I'm unsure if the fact that he used spray paint to paint the car will require additional work to bring the paint job back to a more 'conventional' look. By conventional look I mean a proper paint job that you see off the factory or back from a good body shop.
It's not going to take more work than it would have if the paint was faded or spotty or had teardrops (running paint because it was applied too thick). It's just lots of sanding and filling in imperfections.
I afraid you need to sand entire surface, then paint with primary, then paint with proper paint. Spray paint don't have consistent pressure so its grain is not perfect. To prepare and repaint entire car you need to make some disassemble, masking and drying. So it is a lot of money even in my country (Belarus).