Answering the narrow version, because the broad one does not have a single answer. 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.

TrialNerd_Beth said:

The pattern that distinguishes a bad batch from an exit is behaviour rather than product.

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

laura_annarbor said:

One order arrived in nine days, one was held at the border for a fortnight, and one came back with a seizure notice.

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.

Adding the clinical framing, because it changes how the question reads.

My experience ordering cross-border ordering internationally: I've ordered from a UK pharmacy. Customs can be hit or miss.

Shipping time: 7-14 days
Customs clearance: smooth, no issues
Quality: Janoshik tested at 97.4% purity

International ordering adds complexity but can save 60-80% compared to US prices. Research your country's import laws first.