Writing this once so I can stop repeating it across threads. It is about vendor vetting, and it is deliberately narrow — everything I am not confident about is marked as such.
What is actually established
Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion. Synthesis, testing, and cold-chain shipping have floors. A price well under the floor means something was skipped, and the two things that get skipped are testing and content.
The condition it depends on
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.
The practical version
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.
What I am not sure about
What I actually want to know is how people are distinguishing a supplier having a bad batch from a supplier on the way out. Happy to be told the question itself is wrong.
DataDave said:Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion.
Agreeing with DataDave, and the qualification matters more than the agreement. The pattern that distinguishes a bad batch from an exit is behaviour rather than product. A bad batch comes with communication, a reshipment offer and a batch number. An exit comes with slower replies, pressure toward less reversible payment methods, sudden discounting, and the same reassurance repeated without any new information. The product tells you less than the correspondence does.
If somebody has the primary source to hand I would rather cite it than paraphrase it.
DataDave said:Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion.
I disagree that testing history is decisive. It tells you what a supplier did when they were being watched. Continuity of behaviour under stress — a late shipment, a failed test, a complaint — is more predictive than any run of good results.
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View ResultsTaking the question as asked, rather than the general version of it. 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.
Dr.SleepRoch said:The pattern that distinguishes a bad batch from an exit is behaviour rather than product.
Same position here, arrived at the long way round. One addition: an unstated method makes a report close to uninterpretable. "99% pure" without the technique, the standard and the conditions is a claim, not a measurement.
Ask again with the specifics and you will get a better answer than this one.