Rocky's, If your friend is not willing to groom this poor cat all of the time, just advise her to get it shaved.
Doesn't sound like she wants to put much effort into this.

Some cats just lay in litter boxes, a familure smell, familure place, does she have better alternative spots to lay about?

What about the stools themselves, are they firm, do they look healthy? If not, bring him to the vet for a check up.

You can also revert back to kitten hood, teach her how to scoop in the litter box, you can show her, or get another cat to show her. Perhaps she doesn't like the feeling of that particular litter between her toes when she scoops.