John Bush makes good points about the marketing angle of the color of the car fleet. I don't know enough about the service lives of modern day paints, but apparently the green actually lasted longer than the maroon. According to a September, 1918 bulletin from the D&RG's chief mechanical officer, the green paint lasted three months longer, and cost $1.25 per car less than the maroon which they had been using. (Quoted in Herbert Danneman's *A Ticket to Ride The Narrow Gauge.)
As to looks - well, IIRC, the first coaches on the D&SNG had a pretty good dusting of soot by the end of the day. Don't they have to wash them periodically to keep the nice bright color looking bright? I suspect the same will apply to whatever color the C&TS uses.
One thought about the 'circus' trains that some have mentioned. The D&RGW had oxide red coaches in the 1930's used for drover's service on strock trains. Some of those show up mixed in with the standard green ones on some Civilian Conservation Corps specials.
Charlie