That’s not remotely true. There are plenty of health conditions that affect this. Alcohol consumption can affect it. Completely normal diets with specific foods can affect how stinky your poop is. Non standard but healthy diets also can do the same. There’s a lot more to it.
While yes to a certain extent cutting some processed food and adjusting your diet may help with it, eating a few boiled eggs would set you back massively. It’s not that straightforward.
Extractor, what I’d call a bathroom fan, fair that effectively stops airflow, I’ll go with “close enough to negative pressure for civvies that they fool themselves” (I.e. ain’t actual negative pressure like a cdc lab)
I mean, it literally does. Put something that smokes in a bathroom, open the window, close the door, and caulk the gaps. See how much smoke phases through the door.
I forgot HN isn’t exactly the demographic that tries this and finds out exactly how well it works. I guess for this demographic, I’d suggest telling your tenants it’s okay to smoke in the bathroom as long as the door is closed and the fan is on.