Comment by nucleardog
3 hours ago
Heard similar stories from many people. I have my own--
I was at a range shooting this old revolver with worn seals. Every shot, unburnt (or sometimes burning) powder was flying backward onto my face and arms. I basically took a gunpowder shower.
Got up like 6 hours later and went to the airport to get on a plane. Got swabbed. Came back negative. Got on the plane.
So... yeah, not really sure what the swabs are doing. I have to assume it's more an issue of "they're not intending to detect that" than "failures to detect" because otherwise the repeated misses here are just a little too big to believe.
Most likely there is no quality control for the security process so no one has noticed that the swabs aren't working properly. Most such processes do not have any QA or QC as far as I can tell and the people actually doing the work have no interest in the effectiveness of the process or influence over it.