Barnfish say's...
The McCanns behaviour through out is of people who want their daughter found and they get pissed of by cranks, amateurs and the police making mistakes. Then like us they think certain things should be done on a certain way.
So let's get this straight,
The McCanns are not on trial in a court.
Thus they have no reason to select particular police or 'amateur' investigators for mistrust.
The people in question are trying to find their daughter, they ain't out to corrupt evidence.
The Renault search is available to watch on YouTube, No independent dog handler has 'as far as I know' stated that the search was corrupt.
I have watched the YouTube footage and seen no falsifying of evidence of cheating, the very fact that samples of DNA were later collected from that Renault shows that the search was good.
I find it utterly unbelievable that the McCanns would question this mans method when he's a very well respected police dog handler, he has never implied that the McCanns were guilty of anything, it's just that the McCanns don't like what he found.
So we are now into the realms of the McCanns selecting certain situations to discredit police evidence.
They only discredit police evidence that puts them possibly in the frame.
Thus if the police dog would have sniffed something on Murat's land the McCanns would likely have dismissed that as either bad police practice or evidence that has fallen off of someone else.
On the Renault search when the dog ran away, if the handler would have simply 'moved on' to the next car, thus the Renault not being sniffed 'all the way around' thus nothing found the McCanns would have been happy....
This means that the McCanns are unhappy about a search that was made, it was too thorough, even though they are not experts on canine behaviour or the search methods that are normally applied.
Dog search at Murats

nothing was found
Dog search at Renault

something was found
Are they not meant to be searching for a missing child?
Which again brings us to as you say ....
Barnfish say's....
I can see why there should be a dig. It is the only way of satisfying certain people Madeleine is not there.
The only evidence that she is not there is because of the dog searches that the 'McCanns don't trust'
The only evidence that she might be there is because of this evidence by Birch 'something'.
Now look at this very carefully Barnfish, please don't start discussing Miss Marple etc... again.
This is from Martin Grimes webpage
''The following searches were conducted:
•Five apartments at a complex in Praia Da Luz.
•
Mr. Murat's property at Pria Da Luz.Mr.
•McCann's Villa at Pria Da Luz ( Present occupancy).
•Articles of clothing from Mr. McCann's residence.
•Western beach Pria da Luz.
•Eastern Beach Pria Da Luz.
•10 Vehicles screened at Portimao.''
eddieandkeela.blogspot.co.uk/2007/08/rep...-grime-re-eddie.html
So why do they/you trust him at Murats but not at the Renault?
If they don't trust him at Murat's then they have no evidence against Birch's ground scans, and the need to dig.