For me a *good* Ivory, would be one with a nice clean yellow dorsal stripe, a non-dirty ventral and dorsal body. As far as head soot... does not matter, that is one thing I like about them. I kinda like that the chimney sweep look they have, and it accentuates the contrast of the facial markings... the one I saw at the show was really dingy looking for lack of a better word. Just looked muddy all over.