The value of folklore

Many people rely on Native American folklore about Bigfoot/Sasquatch as anecdotal evidence of its existence, but how reliable is it really? Yesterday I was watching the "Destination Truth" marathon on Syfy and started noticing how often native people from different countries mislead Josh Gates & his crew. One man said he could take them to a man who had large scales from a particular cryptid (I can't recall the name of it now) He indicated the scales were approximately 3"-4" in length. When they got to the man, he gave them scales about half the size of a dime that turned out to belong to a fish indigenous to the area. In another episode, the natives said a vocalization they were picking up, belonged to the cryptid in question. That turned out to be an owl vocalization. Every episode has people claiming clear sightings of these cryptids. Many of which have been a part of the native folklore for many years. When I hear some of the more fantastic characteristics attributed to Bigfoot (invisibility, the power to cause amnesia, etc...) I can't help wondering if some of these people aren't pulling the legs of some researchers. So how much credibility should we really give to Native American folklore about Bigfoot?