I had a neighbor who did this twice a day. Everyday for a week, I scooped the stuff and saved it a bag in my back yard. When he next came over to my yard, I walked out the door, walked past him without saying a word and went and emptied my bag on his lawn. It never happened again.
my next strategey...but I’m going one further...I’m gonna add to the bag with my own dog’s donations!
Maybe even stop by the horse stabl...nah..that might be a bit much.