All the time. I walk through them to get to work.Has anyone on here got a "false positive" from one of these machines because of their carrying habits?
Dont fart, wear stinky perfumes or cologne and wash your hands if you have been doing much and you'll be OK..most of the time.
I got hit for using Tapmagic to tap some holes out. I walked out to the parking lot and walked back in and ended up getting patted down.
Another time I got hit for using Layout dye and had some on my hands. It noticed it. I got patted down again.
Another time I went out to the range to help the armourer take apart some Ar-15's that had the barrel nuts gunked up. I came back in and got hit again.
The sniffers pick up any explosive or flammable vapors or residues.