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.

Correct me if the detail matters more than I have assumed.

anders_CPH said:

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

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.

That is the short version; the long version is somebody else's post.

tony_orlando said:

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

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.

International shipping tracking for cross-border ordering orders: my experience with customs in the US when ordering from overseas:

Held at customs for 5 days, then released.

Tips: always include a copy of your prescription, declare medication properly on customs forms, keep quantities reasonable (personal use = 3 month supply max), and use a vendor who has experience shipping to your country.