safe product to deter scratching on leather?

Rene S. wrote:

Have you tried something simple, like draping a sheet over that part
of the couch, or putting a clear carpet runner, wrong side up?

Does he use his other scratchers regularly? He shouldn't be scratching
the leather if he has a preferred surface. Our youngest (five months)
wasn't happy with most of our scratchers, so I bit the bullet and
bought the Ultimate Cat Scratcher: http://www.esmartcat.com/shopping/Ul...ching_Post.htm

She adores it, and it's a serious piece of furniture. I recommend it.

I have 8 scratchers just like that. Plus a big tree, multi-level
climbing condo dealie, and several different horizontal scratchers.
Rudy uses them all, but he still goes for the couches sometimes. He's
probably thinking, "wheeeeee! Variety!!"

I've gotten some great advice in this thread, and I appreciate it -
thank you all - but I still want to know if there is a product I can use
on the leather that will deter him. Something that won't hurt it (or
the cats, of course). I trim his nails at least twice a month, he still
causes damage. I will not spray him with water, or hit him (of course).
And as to covering up the furniture with sheets, that's not an option.
I like sitting on the leather. I like the way it feels and the way it
looks, or else I wouldn't have bought it. It's our living room, we use
it all the time. Not just for company, it's for living. The dogs like
it, too. :-)

Sooooo if anyone knows of a product I can spray on the leather that is
effective and safe, please let me know. Even if its label advises
against using it on leather, if you've tried it with no damage, I want
to know. Thanks!