The original 1Ds has a tendency to produce green tinted images that are taken in evening sunlight, around sunset. I've taken some pictures around this time that look absolutely ghastly - but at any other time of the day, or under any other type of lighting, the cast isn't noticeable. It doesn't bother me as I don't shoot landscape, but I know there are some custom colour curves that can be downloaded and installed to the camera that help combat the cast.
As far as I know, "the green cast" is something that plagued quite a few early digitals.