Item 6. Coffee Pot cleaning.
In grade school in Indiana I worked in the cafeteria; we would add salt to a dirty coffee pot, then a lemon or lime slice; then ice cubes, then a touch of water.
One jiggles the mess around and around.
The ice cubes are the mass, the salt adds rubbing/friction/scouring.
The lemon or lime adds acidity to cut the coffee quicker.
Sometimes I have seen folks at old Sambos, Dennys, Whaffle House, or Int House Pancakes use a variant of this old scheme.