The figures, for anyone assembling their own picture. Red flags, in rough order of how much they should worry you: no verifiable address, no batch numbers, prices far under market, vendor-commissioned tests only, pressure toward irreversible payment, and shipping with no temperature control.
A narrower follow-up, since the general answer is now clear:
What a vetting checklist should actually contain, as opposed to a list of things that are easy to fake?
Dr.PeteFamMed said:Red flags, in rough order of how much they should worry you: no verifiable address, no batch numbers, prices far under market, vendor-commissioned…
Adding the part of the answer the thread has not reached. 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.
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Browse GL BiochemClosing the loop on my own question.
Follow-up — getting the denial reason in writing was the step that mattered. It named the criterion, and the criterion was a document I already had.
Dr.PulmRoch said:The useful checklist is about verifiability rather than presentation.
Agreed, with a caveat about community reputation: it is a lagging indicator. Reports arrive weeks after orders, so a supplier can look excellent for a month after quality has already changed.