What about the people that go through these "searches" due to a random selection? Are they at fault, too?
Every time I’ve gotten randomly swabbed, I’ve passed the test. I knew a guy who worked for a federal agency that failed the swab test, and got the special treatment behind the curtain. He wasn’t happy about it, but he made sure to wash and rinse his hands very well before trips through security.
In the case described above, the woman had probably used a lotion, hair product, or cosmetic containing glycerin. Nitroglycerin for heart troubles can also trigger the machine, as can fertilizer, and of course ‘gunpowder’ if you load your own, and fireworks.
It’s no secret that the machine looks for glycerin compounds and nitrogen compounds.