Why are casino carpets so ugly? by Tim White
The carpets help take your money.
Everything about a casino is designed to keep you there gambling for as long as possible, including the design of the carpets. Nothing—absolutely nothing—is left to chance or coincidence, and with billions of dollars at stake, casinos will do anything possible, that they can get away with, for an added edge.
The Gruen transfer is the moment when consumers respond to “scripted disorientation” cues in the environment. Spatial awareness of their surroundings plays a key role, as does the surrounding sound, art, and music.
The design of casino carpets has a mesmerizing effect on the brain and keeps your eyes away from the floor and on the games. An added benefit can be that the designs hide stains but not always, as you can see from these lighter colored patterns in Las Vegas:
EDIT: Thanks tofor the Gruen Transfer info!