Body scanners don't work

New York Post:

The body scanners coming to your local airport provide marginal benefits -- if any -- in detecting weapons and explosives hidden on travelers. They aren't worth the cost in money -- let alone in civil liberties.

Despite what their proponents would have us believe, body scanners are not some magical tool to find all weapons and explosives that can be hidden on the human body. Yes, the scanners work against high-density objects such as guns and knives -- but so do traditional magnetometers.
And the scanners fare poorly against low-density materials such as thin plastics, gels and liquids. Care to guess what Abdulmutallab's bomb was made of? The Government Accountability Office reported in March that it's not clear that a scanner would've detected that device.