My "never-will-stain-even-from-heavy-traffic" light azure carpet, a wool-nylon mix medium shag designed for heavy traffic areas, is starting to hold dirty grime and oil from bare feet in a manner that makes the above marketing collateral blush.
I've used the foaming product (set it, sponge it, vacuum it away), and I've attempted to spot it with the aerosol product. The area is just too large and stubborn.
My next step is a steam cleaner but a quick look at the cleaners one uses with this behemoth machine shows the clear warning, "Test in an inconspicuous area before use. May remove dye from some carpets." That would not be an option given the beaten animal path I'm in need of cleaning.
As I done so often in the past, I ask the Collective for their chosen bit-and-bytes of tips in areas that I am not as familiar in lore and wisdom.
The Ranger
-- Beets are the Magical Vegetable; they can be pickled, peared, and julliened and never lose their specialness.