These guys are working for the Cliba Group, the waste management and environmental engineering company of Buenos Aires. They are constantly removing unwanted stickers and posters from walls, poles and signs. It must feel like in the myth of Sisyphus. Soon after the removal new ones will be put up again but at least they make the task of pasting posters all over the city more difficult. Well, this area is highly frequented by tourists so it gets much more attention. These waste and recycling bins stand near the Palacio del Congreso Nacional (Argentine National Congress). A high pressure water jet seems obviously to be the best tool for this job.