Reasons why you shouldn't eat food perched upon by flies. Have you been eating perched upon by flies,well,you are most likely eating food with a lot of germs in it. scientists have warned that flies are actually two-times more likely to spread germs - specifically those ubiquitous, hard-to-swat houseflies. So what's the science behind this? Well, flies eat some of the grossest things imaginable: Poop, garbage,