I went to Las Vegas in 2007 on a business trip. I had brought with me this old Zeiss Ikon with a Nettar lens, because it was easy to carry. I found nothing of real interest to take pictures of, but was out with a couple of colleagues at a mall outlet, and I started to see some potential shots. It was a strip mall, almost brand new, still shiny and without too much evidence of the usual human destruction.
One of the pictures I took was a picture of a store front window with an awning. The place was so new that there were no markings on doors or windows, no logotypes, or anything. Just empty. Flat concrete walls, aluminum framed window from floor to ceiling, and a door. I stood directly in front of it, hiding my own reflection behind one of the aluminum window frame uprights. Perfectly clean, even the sidewalk was untarnished. So I aim, burn off a frame, and then a piece of hamburger wrapper blows into the scene and lands on the ground right in front of the window. I decided to take a picture of the same scene with the trash in it.
To me, after I had printed both frames, the trash added something to an otherwise fairly ordinary picture. It emphasized the sterile and clean shapes and form of the frame. I wish I had the file of the scan here at work. It isn't at all difficult to understand why somebody would not want the piece of paper in the frame, but consider the possibilities of leaving it there. Play with the concept.
My earlier suggestion of pinhole camera use is one where you can, with long enough exposures, take pictures of scenes with people moving through them, and they will mostly disappear in the total exposure. It's a really liberating and interesting exercise, and a pinhole made well can yield super sharp results in case that's a bother with anyone.