My first thought was that the dogs were simply hitting on odors they were unfamiliar with (see list), but I'm not all that familiar with the training process.
Also, some documentary I saw indicated that the handlers can subtly urge the dogs to react as if they are hitting on something.
_________________
This space reserved for dog handlers to deny this:
____________________
And I guess it's a matter of human nature that if you're being a jerk, persons in authority may sit on you for a while under some stretched and strained excuse or another.
___________________
This space reserved for persons in authority to deny this:
__________________
![Evil >:D](http://www.armedpolitesociety.com/Smileys/default/evil.gif)
Terry