Good thing your brother knows about refinishing bows. If he knows about overspray and clear coat, he also might know about smooth-on and how people can cover over damage. Plus some bows have been left in hot attics or otherwise abused other the decades. Sounds like your brother has held this bow in his hands and checked the tips and the other 95% of the bow.
When your brother strings it up and shoots it, he will be able to check for limb twist and any other problems. Does he have a bow stringer?
I will never forget an old Pearson Mustang I bought off the net. It looked fine until I put a string on it, then the limb twisted like a wet noodle. No problem with the finish, but the bow was kaput.
One picture of 5% of a bow is hard to judge. Good thing is, most people are honest when they refinish and flip bows. Most, not all.