Unfortunately, nobody can ask the dogs, a) they never could speak b) they're dead, i,e. they can never be tested for accuracy c) according to their own handler, Mr. Grime: Every alert can be subject to interpretation, it has to be confirmed. The signals of an alert are only just that. Once the alert has been given by the dog, it is up to the investigator/forensic scientist to locate, identify and scientifically provide the evidence of DNA, etc.
Not ONE of the alerts were later corroborated by forensics, which according to Mr. Grime, render the dog alerts meaningless.
True, that's why those dogs have as much/little value as dowsing
Not dissing dowsing - but it's a game of chance - NOT science
If the dowsing rod indicates an underground stream/metal ore or whatever - and one cares to get a shovel out and dig - and finds no such thing.
Then the game is lost - simple as. Try again, another day.
No different to the dogs - they indicate and that indication needs to be corroberated by scientific evaluation - didn't happen in the McCann case.
Game over, woof, woof I'm afraid.