They have been off because of the fading and low saturation of home releases. Also the earlier transfers, which would have been the least faded (i.e. 1982-1985) were very poor and had their own tinting, aside from Laserdisc being unable to display the full colour information and subject to its own custom colour correction.

If you jack up the GOUT colours to the I.B. colour levels you see the DS walls become pink. Which means there is colour in them, that seemed grey because it was so washed out. If you then shift the pink out until the rest of the image looks normal, much of the time you end up with blue and green walls. Either this is how it was photographed, regardless of the actual paint pigment, or this is how it was colour-timed to get correct skintones. But in either case it looks like a coloured DS was normal for most, but not necessarily all, of the shots, to varying degrees of intensity. My two cents.