Quality of exterior finish:
This not only affects how the aircraft looks, it affect the aircraft's value. Paint quality not only affects appearance but aircraft performance. Variation here can be extreme, and significantly affects value. Again, the NAAA appraisal process does this objectively and fairly.

What is the engine worth:
The engine is the most critical part of the aircraft. Requiring routine maintenance and overhauls, engines are important. Again the same plane may have different engines. The NAAA appraisal process utilizes a database of thousands of engine configurations and overhaul cost together with the current maintenance status of the planes engines to assess the engines contribution to the value of the aircraft..