K9 Officer:
"He never entered into that tracking mode," Burgin said. "The odor outside whatever existed outside was not as great as Nancy's odor inside the house. Max was working inside the house, because he knew her odor was more saturated inside the house."
From the book I read on the Search & Rescue dogs. The HANDLERS have to be trained to trust the dog. There were several cases related in the book about humans telling them a person went in one direction, but the dog said differently. The handlers tend to want to trust the human, but the dog labors under no such impressions. They trust their nose, and the humans must learn that the dog won't lie.