I was on a team designing a mobile app and we sometimes had confusing conversations with the project-manager, at some point he told us he was partially color-blind. Specifically in this image: http://i.imgur.com/jJIWv9X.jpg , all three pics look exactly the same to him. This app was basically a monitoring app using the well-known traffic colors of green=OK, orange/yellow=UhOhWarning, red=BigProblemHere.

That incident made us take extra care in designing the app such that we never conveyed info solely with the colors.