Because a dog alerted to the scent of death in the home of Shannon Mathews,
I do wonder what conclusion would have been arrived at, had the child been found deceased in a wood or somewhere else.
Would they have investigated the possibility of the furniture in the home, being purchased from a deceased person?
How could they know that the scent that was supposedly alerted too, was on furniture or who that scent belonged too?
How do you check any antique or pre-owned furniture you may purchase, for cadaver scent? You can not!
There are so many possible reasons for an alert of cadaver dog, that I do not believe any can be reliable, unless a body is found in the location of that alert. Just my opinion, of course.
If people could take the 'dog's don't lie' belief system out of the equation I think people would realise that there is still a great deal of scientific research and work going into understanding just exactly what it is that causes the dogs to react.
Because Shannon was very obviously alive they had to find out what caused the alerts, would they have bothered otherwise?
If her remains had been found or she had not been found at all ... what would that have meant for the investigation and the misdirection of resources into her case.
I agree with everything you have said in your post although I know that dogs do alert in areas where bodies have lain (eg ... soil contaminated by a corpse is used for training purposes and I read that when the containing jar is opened it is possible to discern a scent ... can't find the cite).
Were I on a jury listening to cadaver scent evidence where remains or fragments had not been found ... I would not be a happy bunny.
**Snip
But in the field, VR dogs can sometimes be distracted by “false positives”, such as dead animals, or even mushrooms, explained Lorna. If she can arrive at a greater understanding of the chemistry of odours from human cadavers, then VR dogs can be extra efficient.
https://www.hud.ac.uk/news/2014/august/forensicsresearchtomakecadaverdogsmoreefficient.php