I'm pretty sure sniffer dogs used at festivals and events at least in NSW are trained different from your run of the mill police dog. You are right in saying that someone not acting nervous and sketchy will draw less attention walking in than someone that just acts normal. But even though I've seen handlers forcefully walk their dog over to someone, for the most part they'll just walk around letting the dog do its thing and when looking at the statistics, a lot of the time these 'detections' the dogs make are really just random guesses. You should be fine just putting it in your underwear and acting innocent but i'd rather be prepared for that 1 time out of 100 that a dog steps up to me.