Years of analyzing popular but dubious claims leads to the impression that just about all knowledge that filters down to the popular consciousness is essentially wrong, at least as a first approximation. This may sound cynical, but think about any area in which you have specialized knowledge and compare that to what the average person believes about that area. Now extrapolate that to every other area of specialized knowledge.
I may be skeptical, but I am not a nihilist. I do think the situation can be and is being improved by popularizing science and other areas of knowledge. Experts need to be directly involved in teaching the public about their area, and when they are, popular beliefs can be corrected.
One example is the myth that we only use 10% of our brain. This is still fairly popular, and was recently a central plot element to the blockbuster movie, Lucy. However, Google “10% brain” and you will find nothing but links to sites debunking this myth, at least in the first few pages.