I have older Light Brahma's. Because of feathers on their legs, feet and toes, the scales "lift" and get sand, dirt or other debris under them which can be confused for scaly leg mites.
I also have 2 non feathered footed chickens with my two Light Brahma's, they all roost in the same coop, on the same perch at night.
If the Brahma's had scaly leg mites, my other two non feather footed birds would have scaly leg mites as well.
Scaly leg mites are spread by crawling to other birds perched on the same roost. My two other birds do NOT have scaly leg mites, otherwise I would easily know it.
When treating birds for scaly leg mites, you must also apply vaseline (or whatever you're using on the legs/feet) to roosts to prevent the mites from spreading from one bird to another.