San Francisco recently doubled the number of walls it was coating with hydrophobic paint, which is supposed to deter wall-pissing by making the urine spray back all over the pee-er.
An anonymous citizen journalist crew armed themselves with a full bladder and a video camera and field tested some of the existing coated walls, braving urine-soaked clothes. They were spared a soaking, as the walls did not perform as advertised. They had been coated a mere two months ago (the paint is supposed to last for a year), and seem to have lost nearly all their efficacy in that short period: unless the pee strikes the wall at a very specific angle, there is no visible effect; when the wall does reflect the pee, the effect is minor and hardly noticeable.
(via JWZ)