There is also a market for recycled and semi-properly labeled chips, for example selling low precision grade analog chips as a higher grade or chips tested for the usual 0-70°C operating temperature range as rated for military/aerospace range -55-125°C.

This is harder to catch with QA. A few years ago there was an investigation in the US where they found some examples of such chips in military equipment and also proved counterfeiting beyond any doubt by ordering military grade parts which have never been offered by the manufacturer in military grade - the vendor simply relabeled them.