Germs are tricky little bastards. We as humans go to great lengths to avoid getting sick, but the methods we employ to combat germs are not cross cultural.
In Japan they go to great lengths to avoid airborne illnesses. They wear masks. It is hard to go anywhere without seeing someone wearing a mask. In America, masks are almost never used.
In America, we are constantly aware of the germs from the things we touch. We wash our hands, and use hand sanitizer. We also get way more upset about things like wet door handles than Japanese people.
I wonder if Japanese think it's disgusting and weird that people don't wear masks. It's very rude here to be visibly sick and not wear a face mask. People here wear face masks as a precautionary measure for themselves and the people around them.
Japanese people are not cautious about the germs on their hands. In Japan their are no towels in the bathrooms, you are suppose to bring your own handkerchief to dry your hands on. This leads to people skipping the hand washing part of their bathroom visit. People also use their handkerchiefs as handkerchiefs. People in food preparation often skip washing their hands. The most shocking to me was when I had my blood drawn here, the woman did it without gloves, or washing her hands.