You do know that these dogs don't 'work' all the time? They begin work after the sniffing of the item belonging to the missing person. The dog from Portimao certainly entered 5A, but began working after exiting the front door.
Oh I see ... the dogs and their handlers specifically called in to search for a missing child, just sort of hung around not doing anything in particular while they whiled away the time dropping cigarette ash and shedding doggy hairs all over the scene of the crime while ignoring the primary source of Madeleine's disappearance which may have indicated which way she exited.
In my opinion that doesn't sound logical behaviour for guys with their dogs who really pulled out all the stops on Madeleine's behalf for as long as they were thought to be of use and were on site.
But please have it your way if you think these guys overlooked the obvious of clearing their feet by starting at least one their search at source.
My way of thinking is that the GNR did not turn 5A into a howf for brewing up their coffee and a place to exit from before starting work ... I think the handlers got the dogs to start at the very beginning and I think the amount of hair left on the premises would indicate that the handlers and dogs were there long enough to ensure every centimetre and very nook and cranny of 5A was checked out.
How foolish would they have looked at a later date if Madeleine was found behind a bath panel!