My understanding [please correct me, I'm not a doctor] is that it's recently come to light that there is very, very little evidence, if any, that salt is bad for you (aside from people with certain heart conditions), yet the whole medical profession loudly proclaims that salt is in general bad for you.

Regardless of whether future evidence may demonstrate that salt is bad for you, or that q-tips are bad for you, this sort of thing seems to be the medical field's version of the urban legend. Everybody believes X because they heard someone else -- maybe a professor at school -- stating it, but ultimately it has little scientific basis, and it takes years to root it out. I wonder how often this happens, and what can be done to counter it.