I was in a meeting at work last week where a contractor was going through a Powerpoint presentation about their product, making statements like "it will travel [X] far" and "the sensor will operate accurately" and "our algorithm will avoid common pitfalls".  I was asked for my "expert" opinion afterwards, and instead of questioning every claim they made, I simply said this: 
"The contractor needs to provide evidence for stated claims instead of just assuming we'll believe them because they said it out loud.  In general, there were a lot of statements of fact without any evidence to back them up.  I'm not saying they were lying about anything.  But a simple [plot of results] or [data from a test] would do more to establish a fact than simply writing a sentence on a Powerpoint slide."
It's a little surprising to me that this type of thing needs to be stated.  But at the same time, I have no problem being the person who states it.  I've always been a little skeptical about everything.  And even if the final result turns out to be wrong, at least use critical thinking skills and logical reasoning to make your case.  Arguments from authority and proclamations by fiat are things used by dictators and strongmen.  State your claim, make your case, and prove your point with evidence. #science