We have a butler sink and keep the liquid hand wash on the granite work surface.
My DC and DH for some reason have to get the whole area wet when they wash their hands. I try and dry the area whenever I see it ( I have also asked them to dry the side which falls on deaf ears).
We live in a hard water area so there can be a build up of limescale when the water is left for a prolonged time. The granite is black so does tend to show limescale marks.
I just wondered if anyone had a magic solution.