Quote - Don't get me started on grayscaling the diffusion maps to make bump, displacement, and specularity maps.  I've been fussing about that for fifteen years.  Not that it's done any good.

I assume you mean without making modifications after the initial desaturation. I can see maybe a modified grayscale for a bump map, depending on the texture, but what could one possibly hope to accomplish with a displacement map that's made from the texture. That would seem to serve no viable purpose, given what I usually assume to be a displacement map's purpose.