Psychologist have already figured out what certain colors evoke in us emotionally. Orange = warmth.
Remember what McDonald's seats were all fiberglass red and yellow? That's because they wanted you to eat and GTFO. Those colors draw people's attention so that they will deal with whatever danger it represents. That's why green means good and red means bad, universally. Therefore McDonald's made sitting there an emergency situation. Since then they changed their tune, muting colors, using wood, adding wifi because they realized that people that stay longer buy more. From the wii article:
http://en.wikipedia.org/wiki/Color_psychology