I'm in complete agreement with everyone who says not to do it!
I'm a kitty lover even though I can't keep cats at my current place of residence, but we do own several cats at home.
It will definately hurt them!
Like someone else mentioned there are other options like using that spray that will deter them from going on or near the couches and other furniture. My parents used it successfully with our cats at home, and it doesn't smell like anything (to humans anyway)
Kelly, AWESOME post! great advice!
shopgrl, best of luck with your feline friend