[skeletor_999]

The scientific method is hard to explain, and scientists frequently mention peer reviewed papers when talking to the public. I think that this is mainly to dismiss things like health anecdotes that spread around the internet. We don't have time to explain in detail why your uncle's implausible and untested miracle cure for whatever disease is unlikely to work.

There's no easy answer to which sources are reliable, but it helps to look at what reputable organizations say. They typically base their advice on the majority opinions of relevant experts. Scientists are human, so they are bound to make mistakes, but in the whole they have made demonstrable progress in a variety of fields.