When you think about it, stencils and masking goes hand-to-hand with spray paint art. It could be an intricate detailed cut out stencil or a hand torn piece of poster board, you can't separate the method from spray paint. But is it cheating?
Better yet, did the old masters cheat? No. But they did use technology they had at the time to help them create their masterpieces. For example, they used the Grid System to help enlarge, reduce, or enact accuracy in size, shape and proportion of their subject matter. They even traced by punching holes along the lines of their parchment drawings and they painted through the holes to transfer the image onto another surface.
If the old masters were alive today I bet they would use the modern technology that they would have at their disposal, much like we do. It's okay to use a computer to take an image and enlarge or reduce its size, to copy it onto a sheet of poster board and use an exacto knife to cut a stencil or mask. These are tools of the modern artist.
Spray paint art is not cheating, my friends. It's a chosen tool for some artists to help put their vision on canvas, much like the tubed paints and brushes, tools used by traditional paintiers. A famous artist, Helen Van Wyk, once said that an observer of a piece of art does not care about the struggle that the artist had to endure to create the work of art. They either like it or not. That's all.
It's important to not only learn the methods and technique of spray paint art to help you create, but to also use the tools you have at your disposal to help you create your work of art in the most direct and easy way that is best for you. It is your vision that you are placing on canvas. Make it yours by using what tools you have at your disposal.