The real thread, preventing cats from clawing corners of sofa  

Have you provided a scratching post or other scratching toy? Tried the usual methods to modify the cat's behavior (water from a spray bottle, "No!", etc.)?
If the cat lives indoors and you're considering declawing, please try claw covers first: http://www.softpaws.com

Hi.
A picture of the sweet cat might help.
Best,
Aunt Mark

We would never declaw a cat, plus both of our cats are indoor/outdoor as they have to go and protect their turf.
But they do have both hanging rope wrapped boards and cardboard scratching post for them.
We tried the spray bottle but it didn't really help
They are super domesticated, around 5 years old each, as both were bottle fed from about 5 days old, when we found them them abandoned in the bushes with eyes still closed and covered in ants.
This is the only bad thing they do, they don't tear up carpet or spray or do any other reckless behavior besides the occasional paper towel roll that the male, Blondie, likes to rip up

This might not be a solution that is acceptable to you, but my mother has a cat that claws the corner of her sofa, and he stopped when she placed pieces of clear packing tape over those areas. Granted, she has had strips of packing tape on the corners of her sofa for six years now, but the cat leaves it alone.

We did that! And it didn't work. Ha

Hi.
A friend had a similar issue with her sweet puss. She simply purchased a small framed mirror, and placed the mirror in front of the soon to be clawed area's (moving the mirror, as needed). In no time at all, the little monster was trained to claw only a scratching post... and her dog's eyeballs. My same friends cat poops in the toilet, too (which I find disgusting).
Best,
Aunt Mark, cat lover.
(edited to add a snappy of my boy Mr. Chopper). I'm so proud.

Mark, This is one of them, carol.