I nitpick about little things like accuracy in scientific studies (hear: blatant bias, even admitted by the authors), and only one side of the opinion being funded for studies and not the others.

I myself used to be a staunch vegan, surrounded by friends who planned not to have kids. Well, they have kids now. That triggered my will to study the original documents and find a movement that is fundamentally dishonest.

The worst angst I have is, what if they were dishonest and still right. That would be terrible.