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.
I flew from Green Bay to San Antonio. I had a bottle of water, my toiletries had liquids of more than 3 oz, I had both my laptop and iPad with me and was wearing a coat.
Got to boarding, the agent took my ID and ticket, looked me square in the eye and said, “have a nice flight.” No xray, no pat down, no fluids confiscated.
Saw the agent a while later while I was walking around and asked him why he let me through. I loved his answer. “Your a middle aged white guy probably going home from a business trip. You don’t look Arabic and it’s Friday, so the radicals are at the mosque. I doubt you are going to blow up a plane in Green Bay Wisconsin.”
I was profiled and rightfully so. Israel does it and hasn’t had a problem in 40 years.