They don't even have to be set off, just the presence of the dog allows them to say anything they like. Officer got a warrant to have me taken to a hospital to be "internally examined" all because they told a judge a dog "sniffed my butt" and they thought drugs might be up there. The dog never alerted and the officer even lamented in my presence that it was a "bad dog."

Not like the judge can ask the dog what happened.