What exactly is meant by the phrase "BS discipline"?

I suppose a discipline is BS if in the case of a science, it fails to systematically track the realities of an object of study. In the case of a trade, like business management or welding, then it's a BS discipline if it fails to make its practitioners more successful than those outside the discipline. I'm not sure what kind of a discipline law is.

Taleb's thought, I suppose, is that a discipline is likely to be BS if, instead of directly measuring the capabilities of its practitioners, we tend to measure only indirectly. This only implies that direct measurement is costly enough to outweigh its benefits, however. One reason for its being so may be that there's nothing to measure directly (i.e. the discipline is BS), but another might be that the discipline is so specialized that very few people are competent to judge any given applicant. Yet a third might be that its subject matter is subject to a lot of mind-killing, so that one can confidently judge an applicant without bias.