I had a metal detector run over me by someone obviously in the very earliest stages of training.
Each time she got down my legs to the lower shins, it started beeping. She had me roll up my pants cuffs. Nothing to see. Then she had me take off my shoes, and she held them while running the wand over them. Still nothing. She went back to my legs , but it still beeped as she approached my ankles. It was then that a more experienced TSA-er intervened, telling the newbie, " It's the FLOOR". Sure enough, Denver Intl had a fake marble floor with shiny pieces of metal mixed in to the pattern.
Then the newbie investigated a beep outside the jeans pocket containing my wallet ... perhaps a rivet? She had me give her my wallet, and sure enough, each time the wand got close to the wallet - be-bee-beep! I was worried that my hugely overstuffed wallet would have to be emptied, one paper scrap & business card & photo at a time. But I was saved by another intervention: The experienced TSA-er returned to tell the newbie, "It's your RING!" Sure enough, it was detecting the wedding ring on her left hand, which was holding my wallet. They let me go.
Funny thing is though, I don't remember them asking me, "Would you like to complete a survey afterwards to describe your experience?" Aren't they supposed to do that? :-)