The issue with all the BS around this case is that much of it is secondhand information that came from Portuguese investigations and with interpreters involved - and that is assuming it is not further exaggerated by the press who have been shameless in dragging this case and the family up at every opportunity for all the wrong reasons.
The most convincing evidence in this case is in relation to what is not feasibly possible. Maddie went missing some time between 6ish and 10, but the McCanns were with the group of friends from just after 8. So there is a max 2 and half hour window where if they had any involvement something happened. That window of time is early evening, its light, they have two other children. They had no car and this is a busy holiday resort, there are no witnesses that saw them outside the resort. What exactly can they have done in that window of time where the body would never be found? There is no conceivable way that they could do this and get away with it.