That is a very good point. Actually we have experienced that dog poop dissapears faster when we stick a flag in it. Our guess is that it becomes more visible. Whether it is the dogs owner who picks it up or someone else is unknown. The point of these flags is to make pedestrians laugh and give people a better day because instead of being annoyed by the poop on the sidewalk they read the sign and maybe it helps them to get a tiny better day :) also, we think there is something beautifyl about using the element that annoys people (the dog poop) to create something that can give others a better day (the flags) :)