I got some double sided tape made for putting on furniture to help deter my new little ones. We had to go through a few strips because they are obstinate little buggers. But, they have stopped using the corners of my couch. We have scratch pads and poles placed near those corners still and sometimes they will reach and show how big they can stretch on the couch but will do the scratching on their stuff now.
Oh wow! I love the weird personality traits they get, even if they may make it harder to keep a nice place! Lol