Phrenology for example, most other veiled excuses for one person to feel superior over another. Stuff like ZPE is not taken seriously either and if you do, you are mocked. There are hundreds of such examples, which to my mind are ridiculed for good reasons.
You can't even mention the things you can't criticize without getting an earful of why not being able to criticize them is making our society better and then suffering a withering attack on your moral character.
In other words, the sacred cows cannot even be named.