Inappropriate spraying is a major problem with cats. It is actually quite difficult to stop this behavior. It is deeply ingrained into the psychology of cats. I have seen pet owners go mad trying to find out working methods on how to stop cats from spraying. But, it does not mean that it is impossible to stop cats from spraying. Pragmatic approach is necessary to solve this problem.
There are different reasons why cats spray. Each cat would have a reason of its own for inappropriate spraying. So, if a particular cat is spraying, it is important to find out what is causing that cat to indulge in inappropriate spraying habits. It is worth consulting to vet to find out if any health problems are bothering your cats. If it is true, then simply curing the health problems can stop cats from spraying inappropriately.
When I say health problems, I am not talking just about something physical. I am talking about the psychological health of the cats as well. Cats tend to get stressed and depressed easily. Even seeing an outside cat on the road can cause stress within one of your pet cats. An experienced vet would be easily able to diagnose your cats and let you know if there are health problems troubling your pets.