The job I held could be highly stressful at times, but once you got into a certain groove, listing priorities before non-essentials, it was fine. The biggest barrier I ever found, was the lack of communication, whether it be from the workers themselves or (at times) the supervisors on the floor, who have the difficult task of juggling all the aspects of production. The biggest red flag, was lack of organization or "reacting" to a situation, rather than "proacting", by which I mean they'd wait until a part was completely diminished before requesting a refill, instead of recognizing that they were running low and should replenish in a timely fashion...
A great number of people to work with.
Disorganization and no long-term job guarantees.