I have trouble with before and afters too. I did a couple roofs this week and was making sure to take my time with the pics but mine never come out like the rest of these guys. I think they are hiring a pro to follow them around and take pics.
Try to take pictures that will be well lit before you clean and after. Like the north side and the south side. For what its worth come back in a week and take more. I love a grey roof! It shows so well.