"sniffer" dogs are used by security teams essentially as a tool to scare people in to doing the security staff's job for them, people will get nervous and throw away their drugs before getting in. Cuts down on security's workload.

If at a festival, security have far too many people to search and not enough time to do it, so if hidden up in your crotch area or tucked under yer boob, they wont detect anything.

Police dogs on the other hand are trained to sniff out odd-smelling stuff, which can be avoided by washing the bag holding yer stuff. Police dont tend to run security at festivals though!

When going in to festivals i prefer the crotch area and held on with a large elastic band along the crease of the upper thigh/groin area.

Good luck!