Here is my message to all the so-called street artists:
STOP PUTTING GAS MASKS ON ANY CHARACTER YOU USE!
Another complain is about those recently popular black and white photorealistic wall prints - they are almost always indistinguishable from each other because the technology prevails upon the content in this case and dictates the general style which is often the same.
Sorry for the burst but I have just faced a post featuring both gas masks and greyscale prints.
By the way there are some street art blogs that I read: rebel:art, unurth - street art, Urban Prankster and Wooster Collective. They do repeat after each other sometimes (even using the same photos) but not too often to consider it a problem instead of an oddity.