Having worked as a supervisor and manager I can say /u/HiddenFox is correct. One rotten apple is all it takes to spoil the rest. That's why managers are expected to fire everyone on the shift who worked alongside that one bad apple, which is why it's in the employees best interest to catch the bad apples as soon as possible with audio/video evidence as well so they're covered for liability purposes. It's one of the reasons why some will dispose of unsold food to non-profits organizations who will feed homeless people at their own locations.