I agree, it's one of my pet peeves how science reporters give the impression that some finding is a well-established truth when in most cases it's only the first study to be published on the subject. I understand their need to get a scoop like other journalists, but unfortunately most readers don't have the background (or the time) to evaluate these studies critically.

And when, typically, another study is published a few months or years later that contradicts the original results, needless to say it's not headline news anymore. So a lot of discredited nonsense gets retained in the collective unconscious.