Cats instinctively scratch to sharpen their claws and they do it even more if their claws grow long. A scratching post gives the pet cat the chance scratch should there be hardly any other ideal work surface to achieve this. Great scratching posts why do cats scratch people are typically made from sisal cloth or sisal rope which gives the cat an attractive feeling. Cats can remove the worn and fraying outer layer of the nail and sharpen and hone the claws, keeping them in excellent shape and having them ready for self-defense or hunting by scratching.