I think certain materials feel more scratchable to cats, especially anything rough, which they can get a good purchase on. The scratching posts and boards you can buy have a particularly rough and uncomfortable surface, but the cats love it for cleaning their claws on.
Talisker doesn't particularly scratch the leather sofa, but there are a couple of small groups of holes which are suggestive of him having an unsteady moment, and having to use his ground anchors.
What he really loves is the corner of a cardboard box, there are a few (from the house move, which I've almost finished unpacking... Aham...) which have been shredded by him.