After seeing this video
which purports to be from a national organization regarding their own roof cleaning certification and listening to the questions on the test, which I don't feel relate to roof cleaning very much, I have found something that other contractors may beinterested in.
It appears that there is a form of certification that would likely require more work and effort than the current testing.
See the below listed certficate: It appears that if you can insert your company name and sign it that you can be a certified roof cleaner and have all of the rights and privileges that accompany the having of that certificate.
I thought that I would share this with my fellow contractors who are on the fence. I looked for their website but I think that its not done yet, but the president of the org is a guy named Phillip Ourwalitt.