I read the thirty reasons before the site was taken down. I'm not convinced; there's a lot of "argument" involved.
I also don't like rhetoric being used to bias and reinforce argument, eg. "human cadaverine". Cadaverine is a nasty smelling substance, but it is produced when any meat rots. No difference between "human cadaverine" and "chicken cadaverine" or "pork cadaverine". You can't train dogs to smell rotting humans - it is not legal to keep rotting humans in GB, you have to bury or cremate them.
When "evidence" is represented in this way, it casts doubt in my mind as to the impartiality of all the statements (and there are "holes" in a few other statements, too).
To my mind, the most powerful argument is that the McCanns, as doctors, should be acutely aware of the power of forensic evidence - so if they were "up to something", they would not leave much of significance.
Either way, the British police were involved in the investigation; if there really was "something to go on", I think they would be attacking that evidence.
I took a holiday in that place about a month before the "abduction". You would not expect any crime around there. The local police are not geared up for anything major. The local people are honest and trusting. It would take a crime wave before they tightened up on local security - and if they had a few British style "lowlifes" around, they would have that crime wave.
I've seen other theories showing how Madelaine could have been kidnapped in a premeditated scheme. I found them more convincing than the concept that the McCanns did something nasty.
I'm keeping an open mind ...