This attempt at showing the so called efficacy of the dowsing method reminded me of something I remembered reading about a few years ago. It was about fake bomb detectors which could, it seems, discover explosives, cocaine and even smuggled ivory. The idea that these devices were useful caught on to such an extent that they were used in conflict zones and by governments around the world.
The fake "detectors" - sold with spurious but scientific-sounding claims - were little more than empty cases with an aerial which swings according to the user's unconscious hand movements, "the ideomotor effect."
It actually started its life as a device which was said to find lost golf balls and ended up as a fully fledged bomb detector. In 2001 it was tested by Home Office scientist Tim Sheldon who warned that not only were the claims for this device misleading but that it would be potentially dangerous to use.
However, the Iraqis spent 53 million pounds on these devices and it was sold in places like Thailand, the Middle East and Mexico. Even some UK government agencies were guilty of promoting this device.
It seems that the Somerset based business man, James McCormick, who sold these devices is now serving a jail sentence for fraud, as is a certain Gary Bolton and others who were also part of the scam. The judge in Bolton's trial said of the device "They had a random detection rate. They were useless."
http://www.bbc.co.uk/news/uk-29459896