There is no specific answer for this question regarding the cleanest part of the human body.
- The eye
- Organs
- Under the fingernails
The underside of your fingernail may be the cleanest part of the body given that the nail bed is not exposed to the world. Of course when the nail grows out from the nail bed it stays less clean. Furthermore, there are some bacteria or fungi that can affect your nails, making them less clean.
It seems from the above information that there is no one "cleanest" area of the body. All humans will have bacteria on their skin. Some of this bacterium is healthy and some of it is not. Even the human cells can be outnumbered by bacterium. Internally there are many areas that have bacteria because the bacteria is there in order to clean the system, but it can turn on the body given the right conditions.
One is never as clean as one thinks they are even after a shower, especially if the soap is not washed away.
One is never as clean as one thinks they are even after a shower, especially if the soap is not washed away.