IF the scent report is true, then I think this is important - it is implying that they picked up on a recent scent. The reason why is: IF they were tracking an older scent, they would have tracked all the way to the dad's house since she had been there on the 26th for sure. And many times before that. The fact they turned around indicates that there was a stronger scent they were following. MOO
ETA: Honestly, I think there are various individuals from LE who are updating Billie at different times, independent of each other. And the information is different. Failed polygraph vs didn't tell results at all. We've heard they tracked her trail, then they just picked up the scent AT the hotel. Now it's not being discussed at all - and they're focusing on areas around Dunn... and canvassing the neighborhood... and... it's all over the place.