So, for weeks, someone was walking their dog — or their pony — down our block very early in the morning and not cleaning up after it. The mess happened daily and was gigantic, and always in front of the same three or four houses (not ours). Lots of people stepped on it, too, another hazard of walking while looking at a phone.
I spotted some neighbors discussing a solution and then I saw these, taped to a fence and pinned to a tree:
An exceptionally polite solution — and it's working.