To be honest first picture looks like the pile has laid down (crushed) because of
foot traffic/wear. You see the
glide marks are not uniform across the entire stroke the pile did not bounce or rebound after cleaning. It is sometimes why you'll get chatter even with a glide.
I would bet the fiber in the first photo is not Nylon or Wool.
Wool can have it's pile manipulated.
Another factor is that once this condition has occurred you're wearing the side of the fiber not the face. Therefore it "looks" dirty when in fact it, the area, is just reflecting light differently.
Pile reversal as far as I know is not a wear issue but an install problem that is apparent even before any foot traffic. It's the same reason you're supposed to side match wallpaper too.