Not to nit pick, but ingested drug packets can only be detected by special X-ray or CT imaging targeting the abdomen. Dogs generally cannot pick up this scent either. One would have to be under suspect and pulled into the smoke filled room for special scanning. So theoretically, yes, one could "walk right through"."Don't worry, they can't detect it because it is inside you. You'll walk right through!"
I'd love to see the look on their faces when they are transferred to a jail from the airport.