Thanks as always @fabulousfungi.

I agree the whole detritus/attachment question is framed sort of strangely by Kuo. A picture would have clarified what he was talking about a lot I think.

But he really seems to get that bit from a much older description. I feel like that kind of loosey goosy characteristic being treated as dispositive is a bit misguided where a number of external influences could affect the amount of dirt on a mushroom.

Anyway, it being the only lingering question mark, I've decided to pay it little heed. :)