One concrete data point for the thread. 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.

Following on from chris_chi24 — and this may be the naive question:

How people are distinguishing a supplier having a bad batch from a supplier on the way out?

BethLabQueen 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.

Reporting back.

Update: approved on the third attempt after a peer-to-peer. Nothing about my case changed; only who was doing the talking.

DebRD_ATL said:

The useful checklist is about verifiability rather than presentation.

Right, and one flattering data point from a group buy is not consistency. Consistency means separate batches, separately commissioned, over months.