U.S. Department of Agriculture inspectors are stationed at every U.S. meatpacking plant, where they look for signs of illness upon entry, conduct random samples to detect whether the meat contains antibiotics and where they inspect the organs and skin of the slaughtered pigs for disease.
Even so, they know what any professional interrogators will tell you: A disarming smile, a few seemingly random questions, and a monitoring of body language are far more likely to detect terrorists than brusque treatment and formulaic questions.