I know this question has been asked a bilzillion times. Last year I cleaned my rubber roof with B.E.S.T rubber roof cleaner and it made the roof like new again,but the run off stained the aluminum sid...
I use SpicNSpan, and it cleans it good enough for me. There are certainly products that will clean it down to spotless, to that brand new sterile white it used to be, but at what cost? I can wash it in an hour for a few cents. For me, clean enough is clean enough. I'm not going to eat off it and next month it will be dirty again no matter what you use. I have better things to do. Like go camping!:)
Don't forget the gutters! That's where all the dirt hides.