In my experience the only potentially serious problem is water/rot in the balsa core deck. It's not fatal but requires an expensive repair job depending on the extent of the damage. In particular, check for damage by looking at underside of the deck around the chainplates and bulkhead where the chainplates are attached. Also, check around other fittings bolted through the deck. Another way to check is to tap the deck with the handle end of a big screwdriver. Rotted areas will produce a hollow sound compared to undamaged areas.

The best way to prevent damage is to remove all fittings bolted through the deck, drill out the holes oversize and fill them with epoxy. Then reinstall and re-bed the fittings. Any leaks will then come into the cabin rather than soaking and rotting the balsa core. A surveyor will use a moisture meter to determine the amount of water in the deck.

Another item to check is whether any instruments are in working order. Replacing them can be expensive.

Of course, a smooth bottom is a plus. Also, in-line lowers are desirable. They can be added for under $200 and careful installation of T-ball fittings on the mast. (Cutting holes in the mast always makes me a bit nervous.)