All good posts! I agree that with today’s quality control there are far fewer lemons.
A friend of mine was a master mechanic and was unable to diagnose a rough running AMC car. The owner got another car under the lemon agreement. However, when they took the engine apart just to see what might be the problem they found the cork stopper of a Thermos bottle in the intake manifold. It bobbled around cutting air flow off to various cylinders. Similar rattle problems were often soda bottle welded inside doors.