We have had the same problem with our neighbors as well. I live in a townhome and we share a common area between the building that my neighbor used as a doggy toliet and never bothered to pick it up. After asking them to clean up after there dog and calling the HOA, my neighbor moved and rented out their townhome to someone else, who has been a little more considerate regarding their multiple dogs. Funny thing is a couple of days ago, my original neighbor knocked on our door and told use that we were the reason they moved and we are the reason their tennants are moving. The reason she stated is that we are harassing them about cleaning up after their dogs and she then said she was going to call the police if we continued to harass her tenants (BTW, we have never gone over to them or anything like that, but if we were outside and the dog did it's business, and they started to go inside without cleaning it up, we stopped them asked them to clean up after their dog. Anyhow, my point to this ramble is that it is a community wide issue and something really needs to be done.