It is highly doubtable that there is one person in the world whose skin doesn’t have a scar, a mark, or a spot.
We carry such “tenants” either from birth or as a result from a certain injury. They can be on a visible area or at an area that is less obvious. And of course, there are psychological scars that are invisible to the naked eye…
Here is a collection of tattoos where you can see that the basic idea was not to cover the actual scar but instead to include as part of the concept.