Bacteria!

When I was in high school I had a Biology teacher (1971/1972) who was a practitioner of organic farming long before it became a fad: he had a vegetable garden in his back yard and a flower garden in his front yard, and he always used pigeon dung as fertilizer and openly stated his refusal to use commercial products (i.e.: SCOTT'S Turf Builder) due to their toxic chemical make-up.

And he was always going off about "bacteria".
I learned about not only all the different types of bacteria, but also how omnipresent all these bacterial elements are.
Which can make one quite hygiene-conscious.

Here in Columbus (Ohio) people are constantly spitting on the sidewalks, throwing their trash and garbage all over lawns and sidewalk, and letting their dogs crap on people's front lawns.
...think of all the "bacteria" there is---germs and disease just "floating up into the air" and all around you every damn time you go outside.

Any time I see some lunkhead blowing hockwads right onto the public sidewalk where others also have to walk I think to myself:
"Hey, give me your address so I can come by late some night and dump a bucket of crap right by your front door. And, maybe, urinate all over your mailbox as well."

Of course that's just a fantasy.
One wouldn't dare try a thing like that...
...God knows how many "criminal charges" the authorities would level against you.