I submitted several images in Valencia, Spain: buildings from city of arts. All images are refused cause " elements that might be protected by copyright/trademark etc." ...But in the DT portfolio there are some images as mine, for example : http://it.dreamstime.com/immagine-stock-libera-da-diritti-alba-valencia-image35327556
As it becomes known that certain buildings are copyright/trademarked new rules are applied (any building by Santiago Calatrava for example). Older images that were uploaded before all of the restrictions were known were accepted. If it bothers you, you can contact support and report the images that you are seeing. There are so many images to monitor that many of these older images are still listed as RF, not editorial.