JD, we went on a flighta about three-four years ago. My son had a backpack that he hadn't cleaned out after a camping trip and after the FIFTHT security check some one found the six inch long, ketchup coated kitchen knife the kid had forgotten in his pack Other than losing a few years from shock, I was really suprised that in spite of all the technological screens and searches missed a knife that size, that wasn't really even hidden.
Well, it did thoroughly amuse the other people in line, especially since my poor son was so obviously in a state of shock, white as a sheet, and nearly drooling with fear as the security guy held up the red and suspicious looking "weapon". Still, it just proves that it isn't so hard to outsmart those machines. It just takes a bit of boredom and inattention...