Originally Posted by Mats

I was just thinking about hand swabbing. I've had this as a "random" irritation at Dulles and SFO.

Wouldn't residue be much more likely to show up on bags or belongings? Given the porous nature of hands, sweat, etc., residue would be easier to find on the surfaces of a bag, or perhaps even a coat (not an inner layer of clothing, which is what is tested in an "enhanced" pat-down.)

So the question is: why does this make any conceptual sense?

"We're being unpredictable" isn't the answer. I'd like to know a scientific rationale.

Originally Posted by txrus

There isn't a scientific rationale, any more than there is a scientific rationale for the SPOT program (actually, there's more of a scientific rationale against that, but I digress).

Some company came to the TSA w/a machine & promised that if the TSA spent countless millions of dollars on it, the machine would find those wascally tewwowists that are apparently hiding behind every bush & shrub. TSA said good enough & wrote a check.