Most factory problems are visible before the first order ever ships, if you know what to look for. Inconsistent answers between management and floor staff about production capacity is one of the clearest signals that a facility is overstating what it can deliver.
Other warning signs include subcontracting work to unlisted third-party facilities without disclosure, missing or outdated fire safety and structural certifications, unusually fast quoted lead times relative to order size, and reluctance to allow an in-person or third-party audit at all.
Any one of these alone might have a reasonable explanation. Two or more together are reason enough to keep looking.