Interesting topic! Both of my boys are so messy when it comes to litter box usage. Only, my problem is they scoot their butts up as far as they will go in the back corner of the litterboxes...so they would end up squirting over the edge! The only solution I could find for my messy boys was the covered litterbox. It works wonders for keeping stuff inside. That may be worth a shot with your kitty. By covering the box, you won't have to worry about doing anything to your wall, unless of course the cat is scared of the covered box and refuses to use it! LOL I also purchased a kitty paw mat from Walmart for tracking. It doesn't totally eliminate tracking, but a lot of sand does get caught on the mat, so I simply dump it back in the box.

Pam, that's strange about the pile of cat poo! Wonder how long that's been going on! It seems, someone could have gotten upset a while back...but continues to go to that spot because the smell lingers?? Try cleaning with an enzyme cleaner (or possibly bleach or something smelling of citrus) and see if it happens again. If it does, it may be worth putting a litter box there...and find out who the culprit is!!!