To add to Benice's excellent post above (the first 3 letters apart, spit!), why was an inordinate amount of time spent in inspection of apartment 5a, while inspection of all other villas were whistle-stop?
It seems to me that 'time allowed to search' is the obvious discrepancy between searches of anything McCann related - and other searches.
It's plain from the videos that the dogs do not always go in and immediately identify and make a beeline for a place or object that has been contaminated. If that was the case then surely Eddie would have immediately alerted to Cuddlecat - and Keela would have alerted to the white curtains on her first search - and Eddie would have alerted to the keyfob on his first encounter with the Renault.
The dogs obviously need time.
The longest time spent on any of the other cars was around 30 seconds - and no alerts were made. After the
same amount of time i.e. 30 seconds was spent on the Renault - no alerts had been made. It was only after being given a lot more time and encouragement regarding the Renault that Eddie finally alerted. What would have happened if all the other cars had been given the same amount of time and attention?
IMO it's highly likely that other alerts would have occurred, because (as with the apartments) it's hard to believe that no alertable material had ever been deposited in those 9 cars - either in the factory while they were being built - or by their subsequent owners/families/friends.