You know when you go into a bathroom and someone's taking a shit and it smells bad? Do you know why that is? it's because microscopic particles of actual shit are entering your nose, touching your nose skin, entering your nasal canal. Making contact with the surface of the inside of your body. Someone else's poop is literally inside your nose.
Who gives a shit about some non-existant germs that fly around in the air after you JUST WASHED YOUR HANDS
Despite what you might hear on the giant bombcast, the smell of farts and poop is not literal pieces of shit molecules. They're gas molecules that diffuse in the air.
The problem is if people don't wash their hands or if they do a poor job washing their hands as pointed out in the article. Youre not just smelling shit; you're touching other people's shit which is when the risk of bacterial or viral contamination and infection occurs.