Comment by itronitron

People in general aren't particularly credible, for a variety of reasons.

As I've gotten older I like to think that I've gotten better at questioning/doubting anything anyone (with the exception of several close and long term friends and relatives) tells me, especially if it is second hand information.

A lot of this was learned through various 'inconvenient' experiences over the years. Most people don't double check their sources and just parrot out things they've heard. Confidence is not correlated with accuracy.