I flew into Australia a few years back and was told I had heroin
traces in my luggage at customs. The fatuous officer, who kept
getting more excited as her "sniffer" beeped kept asking if I had any contact with the drug and I said no, none at all.
After about 10 minutes I lost my temper and said "Please...show me heroin." That seemed to jolt her out of her endless cycle of repetitious questions and she said "Carry on" and proceeded to inspect the next tourist in line. Weird times we live in. I guess the point is, if they are going to make the accusation they have the responsibility to quit bluffing and find the stuff.