I think this subject deserves its own thread. Not all boots are worn by people with the same perspective. Peter Lynch recommends listening to people buying stuff, people willing to spend money on a product or service. But what is the motivation of a doctor talking about robotic surgery? They have a serious conflict of interest if their services become less valuable disrupted by the new technology. Their opinion might be honestly heartfelt and still be the wrong advice.
I know from personal experience that I missed making a lot of money on Wintel stocks because, as a professional, I knew they were selling crap. But there was a higher power driving Wintel sales, IT people.
Recently I watched a video about ships lost in the desert, quite entertaining. There should not be any ships in deserts but this fellow managed to get quite a bit of financing to fund his prospecting for gold by spinning the tale – until he was found out.