Originally Posted by
LessO2
essxjay points out a hole in the system. Would not suggest trying that at smaller airports, as many of them are way overstaffed and have plenty of screeners sitting around watching everything you do.
Except that sometimes watching everything you do is the very method of getting everything you want through the c/p (c.f. post #8, this thread).
ETA: Airport size strikes me as less relevant than the ratio of pax : staff : machine at a given minute.