Common reaction when some flies land on meal. A hand is suddenly waved over to drive it away. Then eating is continued as if nothing happens. It is a hard earned meal. Dumping it for the reason of few flies seems ridiculous.
House flies, perhaps the most dirty insect on Earth. Its favorite spots are decomposing matters. Dead animals, decaying fruits and vegetables and animal and human discharges. Carrier of harmful microorganisms like E. coli, Salmonella, Clostridium and Listeria.
The intolerable incidence. Seeing a cockroach and rat feeding on your meal is intolerable indeed. I bet no one is able to eat his food after discovering a cockroach or a rat over it. Cockroaches have a disagreeable odor. It usually hide in dirty dark places so chance of carrying harmful microorganisms is high. Rats on the other hand have an added danger – as carrier of the disease leptospirosis.
How about lizards and ants? Lizards are often seen on kitchen or dining table getting some grains of steamed rice. Their foods are mainly insects but will lovely feed on yours if given the chance. The ants can easily sneak on covered foods, taking advantage of their size and sharp senses. The lizard will immediately run way upon sensing human presence. Ants are driven away by tapping the food bin gently. The dish is still eaten after. They are not as dirty as house flies. Also not as dirty as cockroaches and rats. These two organisms are generally clean. They love dry and clean places. However, they are not exempted from carrying infectious microbes.
Then rats and cockroaches are the dirtiest that we cannot manage to eat foods fed by them. House flies are not as dirty as we thought. We are treating ants, lizards and house flies of equal values. We still eat foods touched by them.