Are you able to do with "not to go on your hands"?
or I must have misunderstood completely.
In retrospect, that really isn't a very clear sentence for those whose first language isn't English, and I do apologise for the confusion.
In America, "go" is sometimes used as an abbreviation for "go to the toilet", which in turn is used as a polite euphemism for the things you do *in* the toilet.
So "I have to go" may not mean that one needs to *leave*, but rather that one needs to use the toilet. The exact meaning is usually clear from context, in much the same way subjects are frequently implied in Japanese: "寒い" is a complete sentence, "it is cold", consisting only of an adjective.
What I was saying is that when I do something in the toilet, I don't normally get anything on my hands. That would be really bad technique.
Even if I did, my skin secretes oils that help prevent bacterial visitors from doing me harm. So do yours. If you shake hands with me, any bacteria I transfer to you are already hampered by my oily defenses, and your own will help finish the job.
Washing your hands takes those oils OFF your hands, and it's a good fifteen to twenty minutes before they return to full efficiency. So while unwashed hands may carry loads of bacteria, those bacteria are largely harmless unless introduced directly to the mucus membranes or other internal structures. Freshly cleansed hands, however, are doing absolutely nothing to combat the denizens of that horrible disease-ridden door you have to open on your way OUT of the bathroom... where they have been breeding and mutating and plotting your gruesome demise for who knows HOW long.
You have to weigh the risks. Is what I would wash off my hands dirtier than what I'm about to touch? My bits and pieces aren't anywhere near as dirty as the unchecked bacterial cesspool on the door handle, so usually, no. But if I were to go berserk and splatter something all over myself, I'd probably be better off washing.
Some people wash their hands, and after drying them use the paper towel as a barrier when they open the door. They can then discard the towel in the next available trash can, and they haven't touched the door. What these people forget is that the air in and around a bathroom is literally teeming with coliform bacteria anyway, so just walking *past* it gets your hands dirty.
Feel like holding your breath yet? Yuk.
And it still doesn't change the fact that bowing is *always* cleaner than shaking hands, but come on, people. It's not like we spit in each other's mouths as a greeting.