Cats are not naughty or mean–spirited. When a cat “acts up” or develops perceived behavior “problems,” care–givers should keep in mind that the cat is most likely trying to tell them that something is wrong. Punishing a cat is really nothing more than blaming the victim. Telling ourselves that our cat “knows better” because he is acting “guilty” is not only untrue; it is little more than justification for our own anger.
If there is one rule in the world of cat behavior, it is that physical punishment does not work and can quickly lead to defensive and fear–based aggressive behavior. Correcting behavior “problems” in cats should only be done with positive reinforcement. In the case of litterbox problems, for example, even verbal correction tends to exacerbate the problem because the cat is already reacting to some type of stress (whether medical or environmental) and punishment just adds to the stress. The most important thing is to figure out what is troubling the cat and then to change the circumstances. In many cases, the answer is simply avoiding those things that cause the cat's undesired behavior.
Whatever the “problem,” you should not wait to get help. The longer the unwanted behavior goes on, the more likely it may become a habit and harder to change.