When I called in a contractor to refurbish one of the toilets in my apartment, he gave us the wildest suggestion to use black tiles for the walls and flooring.  If I had agreed to that, I would have a “dark room” in the house.  In the end, we made a “daring” change.  Not all black though.  Just black tiles for the floor.  And white tiles for the walls to give a more spacious effect.  Of course bathroom vanities  in white to match.