When I was a young kid, there were two mysteries of life that never made sense to me:
1. Why is it that when you wash your hands frequently, they become more dry?
2. Why is it that when you drive your car through the rain, it becomes dirty?
The punch line of the story isn't that these apparent paradoxes are solved when one becomes an adult, it's that these are the types of issues that children process as they try to figure out this thing called "life".
And that may help explain why children don't understand the importance of taking a bath or of washing their hands after they use the rest room.