Thanks for the detailed response, Poly. I think I've now got a better handle on "mud". It occurred to me whilst reading your post that perhaps one way to describe it would be that you are aiming for monochromatic colours (from physics, a monochromatic laser is one of a single frequency).
It's interesting that you comment about the underlying tissue in daylilies influencing muddiness and higher ploidies decreasing the "whiteness" of near-white blooms. From my understanding, that is effectively opposite to how it works in Cymbidiums - higher ploidies of the white species and hybrids tend to have a more solid, higher-quality "whiteness" to them. The layer above the base colour layer is the one that adds "muddiness" (typically in greens) and it is affected by temperature.
