I have never had pets, but recently a friend of mine was in serious trouble and asked me to care for her cat.
I did my best to accommodate it as well as I could. The house is vast, has a beautiful garden around it, and as suggested I bought a big cat tree, toys, treats. The cat has plenty of food, water is refreshed regularly, and I change both litter boxes every few days. The cat gets plenty of play time both with me and my flatmates, and is free to cuddle with any of us at any time. It is even allowed by one of my flatmates to sleep in bed with him at night, although it has a dedicated shelter and all doors are always open, so it is free to circulate around the house as much as it wants.
We essentially haven't constrained its behaviour in any way. It is free to do whatever it pleases, except scratching the sofa. However, since it was here, we had no way whatsoever to prevent him from doing that.
I will be honest: reading on the internet how to handle a cat is frustrating. It seems like no form of negative reinforcement will ever work. Every blog post, article or forum question I found seems to imply that good behaviour should be encouraged instead.
I bought scratch posts. I wrapped planks of wood in cloth and left them around the house. I put treats in the right scratching places. I went as far as scratching the posts myself in front of it, proposing treats as a reward for it scratching too. No dice. Delicately placing its paws on the scratching post only made it angry.
I wrapped the couch in expendable blankets and covers. It still finds a way to remove them, ignoring the scratching posts right next to the couch, and scratch under the blankets instead.
I am frustrated, and I am exhausted. I am not significantly attached to that couch, or any other thing in the house, but I cannot stand the principle that my life should now revolve around a cat, without me being able to put any condition whatsoever on its behaviour. I want to be a good friend, but I didn't choose to be a cat owner, so I am lacking that sort of Stockholm Syndrome some of my cat-owning friends display towards their pets.
What do I do to save my couch, calm my nerves, and make that damn cat happy?