I LOVE this! I have a similar problem in my community and have posted all too often on the community FB page asking people to pick up their poop (I'm "that" person). Not only is it rude and disgusting, but my dog is obsessed with eating poop and grabs it faster than I can stop her - poop mouth dog thanks to these irresponsible owners. I absolutely love your idea of putting up flags - I may start doing this myself, which would not only bring attention to the problem, but alert me to the areas to keep my Ethel away from. And don't even get me started on the retractable leashes (face-palm). I recently purchased a "leash sleeve" on Etsy that reads, "I NEED SPACE" in black ink and bright yellow background. It has been helping somewhat - if you want the link let me know :)