My vet told me to use a spray bottle with water but add a bit of lemon juice to it. The cats really hate it. Now I just say down and they are GONE! If they go into my quilting room and don't want to come out ( I keep my bottle next to to the door and all I have to do is spray it in their general direction and they are out the door in a flash!
I have a problem with one of my cats scratching my furniture. I use tape to cover up the sides. She has a scratching mat that she uses and a cardboard one with the catnip under it that she loves but she still does it. I keep her claws short but she drives me crazy! She even will scratch up magazines. papers and books so I have to keep those away from her.