Mine have stopped scratching the house altogether since I got them the cardboard scratch pads. Put catnip on them, get a few large ones and put them around. Sticky tape will work too, but duct tape will leave a residue. Mine also got their foot pads stuck on it, and eventually clawed it down.
This has also worked for me every time - protect the scratched area. I get the boxes of Industrial Strength Velcro at WalMart, cut off pieces to cover the areas, then stick it on (just one piece, not joining the Velcro). IT sticks, hard, to anything slick, and they can scratch it all they want - it's so tough they don't make a dent. And when they learned it was there, they stopped there, too. I guess it's not a satisfactory surface for sharpening paws.
You could also try bringing in a log (make sure there are no bugs on it, of course, lol).
I never had any results with the Off sprays. I'd check with your vet on this, whether the hot pepper is safe or not. Cats will not go near citrus smells, either.
There is a very good site called "The Cat Site." There is a board specifically for behavioural problems. I'd recommend signing up there and posting. Lots of information there.
One last thing - never punish your cat for scratching. He won't make any association except fearing you. In his book, he is doing exactly the right thing by sharpening his claws. I doubt a spray bottle would help any, since he won't know why he's being punished. I do find that a sharp NO and clapping my hands will eventually educate them.
I've been long-winded here, but with 7 cats, I know how they can destroy things. But they can also be trained. I hope you have good luck with this.
There are also those soft claw-covers you can get.
