I think a problem is when posters post things as fact, when they really aren't. This then gets picked up by media people who lurk here and before we know it, almost word for word, posts on here appear in the media.
It was especially telling in the Germanwings crash thread when people were posting info about mental illness as fact, when actual mental health professionals we're telling them they were wrong. Same goes for other areas when actual pilots are telling people, who've never flown more than a flight sim in their life but post as if they know everything, they are wrong.
Problem is the sensationalism that often comes from the uninformed sounds far more juicy than the reality often is and this is how misinformation spreads.