Most cats can be trained to scratch appropriate posts and trees with few problems. The most common reasons for inappropriate scratching are:

1. The post is too short/unstable. A good scratching post should be at least 3 feet tall and have some kind of sisal fiber covering. Carpeting encourages scratching on carpeting, which just doesn’t make a lot of sense. Floor to ceiling cat trees can be found for a variety of prices on eBay. Cat trees with perches can be hammered together or purchased.
2. The cat’s nails are not trimmed. Nails should be trimmed every 10 days or so. If you are afraid to trim nails have your vet or groomer show you how to do it. It is very simple and can be done when the cat is sleepy or relaxed.

For more extensive information about resolving scratching behaviors, trimming nails and declawing alternatives, please see:
www.catsinternational.org
www.declawing.org
www.softpaws.com