Having said that... I bet a red tent performs as well as a green one!
Having been a fan of "discrete" for many years with a dark green Spacepacker I eventually bought a red tent for the simple reason that I'd decided on a Tarra as a paddling tent and I could get one in red at £425 or in green at £585, so to hell with discrete!
But while green is clearly better at blending in (which is a real concern for a lot of wild camping, especially when it's not that wild), if you don't need to blend in I now actively prefer the red because it gives a warmer quality to the light inside. This is purely psychological, of course, but I really do find it nicer inside on a cold, wet morning.
Pete.