In the spot market, refurbished and counterfeit parts are the buyer's biggest headache. ATL suggests four initial screens: appearance, marking, packaging and channel.
More reliable is professional testing — X-ray to inspect die and bond structure, electrical testing to verify functional consistency, and surface analysis to judge whether marking and material match the claimed date code.
The only durable defence is sourcing from authorized or audited channels, backed by an inspection report for every lot.