I had an awesome neighbor around the corner from us years ago (he & his partner moved, I was really bummed because they were great neighbors) who told me once about a serial dog pooper who kept leaving presents in his front yard. One time, my neighbor saw the guy do it right in front of him. I mean, my neighbor was out in the front yard watering his plants (in his bathrobe, pajamas, & slippers, yet another reason why he was an awesome neighbor! haha!) and this guy walked by with his large dog. The dog decided that he needed to poop and proceeded to poop right in front of the neighbor IN the neighbor's front yard.
Neighbor said to the guy, "I hope you're going to pick that up."
Dog guy said no.
Neighbor said, "You better pick it up. It just pooped on my property."
Dog guy said, "But I don't have a bag with me."
Neighbor said, "That's not my problem. You have 2 hands. Use 1 of them to pick it up."
Dog guy said, "That's disgusting! I can't do that!"
Neighbor said, "But you think it's ok to walk by here every day and let that dog of yours poop every day in my yard and for you to leave it here for ME to pick up?"
Dog guy said, "Um..."
Neighbor said, "Pick it up right now. I'll give you to the count of 3 and then I'm spraying you with the hose."
Dog guy said, "You can't do that!"
Neighbor said, "Watch me."
Dog guy then decided it would be wise to pick up the poop. With his bare hands. And he carried the hot poop in his hands all the way home. Nobody ever pooped in neighbor's yard ever again after that!