Fiberglass - check for bubbles in the boat, check for any cracks in the boat and check for any spider cracking. If there are any of these things don't ask for a price deduction, just leave. These problems can be fixed, however once they occur, then they are sure to occur again. Wood - this is the worst boat to take care of. If you do not have a garage or know someone that has a garage then do not buy this boat.
Water is definitely the worst enemy of wood.
No warping, no give in the bottom or the top of the boats planks. And also no give within the inside of the boat. Very high maintenance and can cost more than the boat is worth. I do not recommend a wooden boat at all. Also check to make sure the electrical system works.