Food held, cooled, cooked, or reheated outside safe temperatures, letting dangerous bacteria multiply.
Dish machine or sinks not set up or working properly, or missing sanitizer test kit and gauges.
Plumbing not installed or maintained properly — leaks, mop sink issues, unserviced water filters, or missing backflow prevention.
Scoops and other in-use utensils stored improperly (e.g. handle down in the food).