You can achieve a very glossy and servicable finish out of a spray can IF you want black or white. About 3 years ago I used the Rustoleum Appliance Epoxy in black to paint a fiberglass stock and it still looks good today. It's much tougher than typical spray can paint. It also takes several days to fully dry so you need good weather and a way to protect it during the drying process.
In my opinion, the most important part of the job is the prep work - proper sanding, priming and a dust-free painting area. Once you have that, you're 90% there.