Joey The Mysterious Cat

I've been helping a neighbor while they're on vacation.  Every three days I go to their house and take care of Joey, the mysterious cat.  I've been there 4 times so far and I haven't seen hide nor, well, actually, I have seen the hair of him on one corner of the couch.  If it wasn't for the tan hair on the couch cushion I wouldn't know what color he was.  He refuses to show himself to me.  I give him fresh water.  I give him fresh dry food.  He never eats all his food but he likes it "fresh" so I have to mix the leftovers with the new food and give it back to him.  I clean out both of his cat boxes. As cat sitting jobs go, this is perfect for me as I am not a fan of cats.  I like Joey!  He's the best cat I never met.