If that is aluminum corner armor, I would expect rust underneath it, unless the owner removes it every year and touches up the paint. Electrolytic corrosion happens when dissimilar metals are joined, and in this case, steel loses.
The other thing I would look for is internal frame rust. If you or somebody you know has a borescope, stick it in a frame hole and inspect for rust. If the first owner was fond of fording rivers and immersing the frame, you will see that inside the frame.
Is that hardtop painted gray, or just really faded?