When I was young a Family member gave us one of their cats, he was declawed. We had tried every trick and litter to get him to use the litter box. He refused, and for the 10 years we had him he would only go to the bathroom on a black bag. It got me thinking, I think either due to loss of feeling, or extreme sensitivity in between his front paws probably made going in the litter box painful and probably attempting to bury his poo hurt in between his paws. I would never declaw a cat, ever!