Floors are not necessarily green and ceilings plain. I went to a talk once on casino design and the thinking is you want the floor and ceiling to be colorful and loud, while what is at eye level should be in neutral colors. That will keep the eyeballs straight ahead on the more soothing colors, where the player will more likely be distracted by the games. Of course this is getting outside my area of expertise. I welcome other comments on this one.