This one has a reasonably settled answer, so here it is. 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.

NurseKim_ATL said:

Prices dramatically below market are the strongest single signal, and the reason is arithmetic rather than suspicion.

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.

SurmountFan_IN said:

The list price and the price I actually pay differ by a factor of six depending on which of four routes I use, and none of that is transparent from…

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

From the other side of the consultation, briefly.

Telehealth prescriber review for cost and coverage: I've used 4 different telehealth platforms to get my GLP-1 prescription. Comparison:

I settled on the one that required labs — it shows they care about safety, not just prescribing volume.