Your list of concerns can be endless. Let break a few down:
Hulls: You can never go wrong with a solid glass hull. Solid glass has no issues.
Cord hulls are also fine, however you must do your homework. A quality cord boats has solid fiberglass pads in every area that a thru hull must go through, such as rudder posts, transducers & water intakes. On an inspection you will be able to see these pods. If equipment was added by the owner with random holes drilled for things like a washdown pump directly through a core surface you could have issues.
Moisture meter checks are not always on the money. In freeze weather they will show negative and in hot weather if a boat was recently hauled may also show moisture.
Another good thing to look for in hull inspections is cracked above water line on thru hulls for pumps and such. If the fittings are cracked or damaged it could mean that water was in that area expanded and cracked the fitting.
Therefore the first thing you should inspect is the hull. If the hull is sound then you move on.
Top side about 99% of all boats will have corded topsides. Expect some moisture around rail fitting, chair stanchions. Antennas & such. A little top side moisture is expectable; after all you are buying a used boat. Walk step and test all the deck areas. If you have soft spots under foot. Donâ€™t write the boat off just use it to you advantage. Repairing top side core damage is not that difficult and it is not structural.
Fuel Tanks: A big eliminator and overlooked problem are the fuel tanks. Aluminum fuel tanks last about twenty years. Replacement of tanks is very invasive and even on survey they can pass only to fail a year later. Use great caution on fuel tank inspections. Fiberglass tanks are never an issue, they last forever. However in some boats the ethanol in the fuel can affect the fiberglass tanks so this is another area to look at.
Engines: Motors can also be time bombs to second buyers. Oil sampling is very subjective and often not accurate unless you have the base lines. Big things to look for are discolored engine paint due to excessive heat, rusty oil pans that are to close to the bulge and are failing. Lack of full RPMs during a seatest & the creeping of temperature gauges under load.
This list is endless so I will stop here wait for comments & posts and then go on the next levels of concur.