This is quite interesting. This pic is old but I still see this.. All new TV's, mid 90's and up, seem to show the sky in Super Mario Brothers purple. Older TV's show it blue.
The screen on the left isn't a TV, it's a Commodore 128 13" Teknika monitor (which is not overscanned - for computer use), and it shows the sky as blue, like all older TV's show the sky.
Both are tinted correctly, but why so drastically different in the color decoding?
http://img.photobucket.com/albums/v3...n/nescolor.jpg
And it's funny, even emulators show this differently too! Just do a google image search on the game, and see how the color appears different in almost every screenshot.