Dr. Dwayne
Self proclaimed tagline king.
I don't buy that the Portugese authorities would take the easy way out and blame the parents. Essentially they are concerned with their image as a tourist destination. "Stitching up" tourists for crimes they cannot solve does not help them achieve the tag of desirable tourist destination.
A lot of the questions they asked were based on evidence that British authorities found, and none were leading or an obvious ploy to accuse the parents as the culprits.
The Mcanns have used the media very well throughout this. I recall the time it was first suggested they were suspects the media in Britain went mad for the most part. It seems to be a more recent thing that people are beginning to question their involvement more.
Sadly it's a tactic that police forces use far too often. Keep in mind that it's not only the police but the judicial system that has an interest in obtaining a solved case/conviction.
As for their status as a tourist destination; missing/abducted/dead children don't help that too much either, especially when the authorities are unable to solve the case.