It's more impressive that dogs can just drink out of rivers, lakes, puddles etc and not get sick

Imagine the power you'd have if you could walk into a room and make everyone sick by farting

Something being stinky or something being a germ doesn’t automatically mean they can harm you. Lots and lots of bacteria exist that can’t hurt you that you’d find in a digestive tract, and maybe a few that could, especially if you ate them. Beyond that, lots of things like scent particles are airborne but not all harmful germs are airborne, a few are but this is very uncommon in the digestive tract, as long as you don’t consume them, they’re not going to harm you in almost every case.

If something was coming out of your butt that could genuinely harm people just from inhaling you would likely be a very sick person with a pretty rare and probably scary infection.

Lots of the stink from the digestive tract is also not from germs at all, that’s just what food smells like once it’s broken down, same as if you left it in the fridge and it rotted and got stinky.

Have you ever picked your nose?

You’re good, don’t worry.

I don't think you can get sick from smelling shit or assholes. You'd have to lick them.

Dogs have anal glands which is part of what they're sniffing when sniffing each others rear ends.

That’s not how bacteria are transferred. They aren’t just wafting off the turd and going airborne. If you place a shit in the vicinity of a Petri dish in a sterile field, it’s not going to grow anything.

Luckily, there's really not many pathogens that cross from poop to the airway.

Then, the sinuses and the mucous orifices produced there are part of our immune systems, as well as dogs'.

From there, the lungs have a similar level of defense, so the chances of sniffing a bunghole resulting in a disease are extremely low.

Even with direct nose-to-anus contact, there's very low risk. The stuff that grows well in the colon and poop just aren't evolved to set up shop at the other end, and vice versa.

Skunk spray your diarrhea for maximum effect

"that protect them infection"