@talk72000,
I would guess that it is impossible to be clean enough. And maybe, as some suppose, we're too clean, because, they say, our bodies have over zealously histamines reactions when presented with mild environmental stimulus. But even if we cleaned better I assert that it would not be good enough to protect us from disease and dying.
It is my opinion that man has an over inflated ego. Many suppose that we may destroy ourselves and our world. I think this is a prideful position and fails to acknowledge that nature supersedes us. Of course we're bound to eradicate some species as we muck about this planet, but many of these species weren't that successful, not like the cat or dog that is successful by virtue of its cuteness and companion ship. Humans believe they can control rats, cats, dogs, cockroaches, bacterium, lice, mice, wolves, salmon, kudzu, dandelions, grass, and on and on. The control is an illusion.
I know of people who've worked in field hospitals, and in places where there was no sanitation. If faced with loosing a leg to gangrene or dying many patients will choose the operation even if the hospital has to use washed bandages, has dim to no lighting, and there are flies everywhere. The one person that I'm thinking of worked in Pakistan for 25 years in such conditions.
One person I know gave up his job to become a homeless person in America, starting in Florida, moving to Washington, and then to Alaska. He told me he never got sick.
Because of incidents like these I'm inclined to not believe cleanliness and sickness are strictly inversely proportional. A healthy immune system must have some factor in the equation, and immunities are acquired through disease.