hello friend
try a bit of table pepper or something that will put a spicy scent in his nose. That dosent hurt them as they wont get enough of it up their nose to hurt them before they scamper away from it, it just discourages them from using their favorite "spots". If hes choosing to use all of your spots then that wont be a solution

on another kinder note that dosent have anything to do with poo in unwanted places.
I have a cat that looks similar to yours he weighs about 25 pounds though, how fat is yours?


edit:sorry the pic is so dark Ive lightened it in photo bucket 3 times (the room was dark when I took the pic) and replaced the tag but its still just as dark as the original....
Ill take a pic of him so it can be seen better tomorrow.