Sorry, guys, I have been away for a while. I was saying that back in the original scenario, the ball was by some unraked footprints. The lie under the ball was good, but in taking a normal stance the player would have set one of his feet on top of a crest of one of those footprints, which would have raised his foot an inch or so. In the shrewd act of digging in his foot, the golfer has lowered his raised foot to a more level position, hence improving his CATS ("meow!") and improving his stance, thus his opponent has a legitimate reason to call penalty.
"Did you dig your foot in to level your stance?"
"Yes, but I'm allowed to dig in my foot to test conditions."
"Yes, but you cannot improve your stance."
"What do you mean? So in this case I cannot dig in my feet at all?"
This is indeed very murky.