It is good Netiquette to inspect used cars. Do look under the hood of cars.
Car Inspection Netiquette Classifieds
Inspecting a car means looking under the hood and at receipts. Ask a seller for service records. Visually verify any work that the owner claims they had done to a car. Test drive the car in all gears. Walk around the vehicle to make sure all the lights work. Check the spare tire. Look in-between the seats.
Classifieds Car Inspection
The radiator should look new if the owner says it was replaced. Receipts further evidence the work done. If the spare tire is missing find out why. Look at the emissions tests. If you are unsure about anything take the car to a mechanic. The cost of a checkup is far less than purchasing a car that does not work.
Car Inspection Netiquette
Inspect used cars thoroughly because they generally have problems.