10. They don't always clean as often as they should

Health inspectors routinely visit supermarkets to look out for the red flags that may signal unsafe conditions for your food. But you can do a little snooping yourself. Flies in the produce or meat departments could be depositing bacteria on raw food. Roaches scurrying across the floor could also be harboring dozens of different diseases. And of course, check the shelves and products for dirt and grime—cans that are covered in dust may be an indication that they’ve sat around past their shelf life.