The first "wall" is a chain link fence with slats. The second one is a concrete block. Do either of those spots actually have the "pee repellent" sign on them? Is there another nearby wall that is more of an actual wall?
Also, a squeeze bottle of water should work just as fine for the test.
If you don't use real pee, someone, probably someone who convinced the city to pay for it, is going to claim that it's not a valid test because of reasons.
Piss Off (TM)
The first "wall" is a chain link fence with slats. The second one is a concrete block. Do either of those spots actually have the "pee repellent" sign on them? Is there another nearby wall that is more of an actual wall?
Also, a squeeze bottle of water should work just as fine for the test.
If you don't use real pee, someone, probably someone who convinced the city to pay for it, is going to claim that it's not a valid test because of reasons.
Why don't they just electrify the chainlink?
Or do the French thing of just putting a urinal on the wall.
Oh, The Treachery of Images.
Where is your sense of wonder, Citizen Scientist?