something Ive read: The dogs training involves scented chew toys and balls. The dog learns the
scent fast. This training is coupled with voice encouragement/commands the dog to to have a stronger response. Something like "find it" or "get it" which the dog associates with its task.... So the police walk the dog around your car, mutters that key word, the dog elicits the response and well. You know what happens next.
Thats the abridged version
Drug dogs and illegal search technique