This idea is extremely ingenious but I have my doubts that it ever worked as well as is claimed. Ogilvy & Mather Group spray painted Hong Kong streets with QR Code advertising that only shows up when the pavement is wet (video below). Using water repellent spray meant that when it rained commuters could see the message “It’s sunny in the Philippines” and a QR Code that resolved to discount deals from airline Cebu Pacific.
In the video the agency claim that online bookings increased 37% which is difficult to believe for two reasons. Firstly the lack of contrast will make the QR Code difficult, if not impossible, to scan in most conditions. Secondly the QR Code uses a Google short URL which enables us to see the scanning statistics and the total number of scans showing is only 89 (screenshot below).
However the campaign may have been a success through press and TV reporting, much like this QR Code haircut from 2011.