I mean if I tell you about the taste of a peanut butter sandwich, how do you tell whether I actually ate a peanut butter sandwich? Or I just read about a peanut butter sandwich??
I mean presumably you could just ask 'how do you know that?'. But also whats to say you arent just making it up in the first place and have never had peanut butter. Thats why you should be critical of information and find trusted sources.