Power washing can definitely be effective, but it depends a lot on the equipment and the person operating the equipment. It also depends on what your goals are with power washing. For example, the equipment and methods used to clean a roof might be different than what you would use to steam-clean an oil stained garage floor. Check out this article for more information about what makes some pressure washers more effective than others: http://www.phoenix-pressure-washing.com/pres...