Thanks everyone for your comments. Who knew the subject of cleaning up dog poop could be such an interesting topic?
By-the-way I was walking on this street last night (without my girls, too hot) and some neighbors walking their dog started talking to me about this sign. (A sign like this is an unusual kind of thing for this neighborhood). They said they did not like the sign, but could understand the frustration about people not cleaning up after their dogs. Just wonder how long this sign will stay up?