@snowded blogs on Negative evidence and the village idiot syndrome
People who should know better (so-called scientists) make this problem worse by using the phrase "no scientific evidence". For example "no scientific evidence that eating infected meat carries any risk to humans" or "no scientific evidence that mobile phones cause headaches".
This creates the impression that there may actually be lots of evidence, but we can safely ignore it because it hasn't been collected or approved by somebody in a white coat.
Just as some kinds of evidence are inadmissible in a court of law, so some kinds of evidence are inadmissible in a scientific journal. Among other things, this leads to publication bias, where people perform calculations based only on the data that have passed through some publication filter, which is then systematically incomplete.
See my comment to Science isn't about Checklists