I've read recently about the pseudo-scientific way Nazi Germany and others approached race. I wonder if there are still similar things - ideas that we consider scientific but actually aren't.
I worked on a device that used kirlian imaging to scan your body's health using only "finger prints". The founder of the company could tell from no prior knowledge that I had to pee at the time of the evaluation and I also had a back injury a few years ago. Lot's of people would argue this isn't scientific, but we used known diagnosis from current medical practices related to heart disease, we were able to establish 95% confidence whether a person was at risk of cardiac failure just based on their finger tips.
I've also had some experiences with alternative medicine where it seemed like practitioners could determine surprising things about me, but it's also easy to get fooled about this (including patients, practitioners, or both fooling themselves). It would be great to subject this kind of thing to blinded testing.
Most political biases. That is, people think that their own opinion is based on a sound understanding of statistics, but in reality they are manipulated by their news outlet of choice. It happens on all sides of the political spectrum.
That's the closest similarity that i can come up with at the moment.