My wife and I painted one wall (except a 10” border) in each room of an old apartment a different colour (except the bathroom, which was completely bright acid green and the kitchen, which did not have a wall suitable.) The living room got a nice dark taupe. The bedroom wall was light blue. The second bedroom received a sort of banana-y yellow.

Guests were usually stunned by the bathroom. Every wall and ceiling surface, except the tile in the shower, was roughly this colour: greeeen

The down side is that it was also difficult to cover up afterwards. :^/