BethLabQueen said:The pattern that distinguishes a bad batch from an exit is behaviour rather than product.
BethLabQueen has the substance of this right. The condition it depends on is worth stating. The useful checklist is about verifiability rather than presentation. Independent test results commissioned by buyers rather than by the seller, consistency across multiple batches over time rather than one flattering report, a physical address and a company registration that resolve, batch and lot numbers on the actual labelling, and a shipping practice that matches what the material needs. Everything a good-looking website provides is cheap to fake; none of the items above are.