Tough question to answer. When it comes to things like outworldly monsters, aliens or things like that, I highly doubt the media has any kind of decent grasp on how such creatures might act. The reason is, aliens in movies and stories are way too human, which shows right away that we created them. Star Trek always makes me laugh with that. All their races are so human, or ideas of certain human attributes rendered to perfection manifest. (Spock is a good example, as are the Klingons.) The only thing that usually makes aliens stand apart from humans are their looks, although I thought ET and Encounters of the Third Kind were pretty unique.
More often than not, alien sightings and the like are merely a collection of grossly misinterpreted sleep disorder experiences, and highly reflect the demon possessions or vampire visits people claimed to have been a part of in the middle ages. Which again, shows that they are creatures of the human mind, used as a sort of explanation for shit we don’t get.
The best thing I’ve seen is James’ Cameron’s Alien films, where they act more like ants than humans. That’s plausible, and fits well in the movies, I think. Predators on the other hand, are basically just all of man’s hostility and brutality turned into a creature.
I also doubt a yeti or a bigfoot would act the way they’re described to act. Even if they are descendants of prehistory somehow, the human fashion they often seem to show, such as compassion towards the weak, tribal behaviors or emotive fear that transcends survival kind of contradict what they’re supposed to be.
The undead and other related creeps are a different matter when it comes to my argument however. A vampire used to be a human, a werewolf (Not undead, but it belongs to the same ’‘spectrum’’.) is a human afflicted with what is generally agreed upon as lycanthrope, and zombies were also human at one point.
While a zombie is very unlikely to present human behavior that goes beyond survival, it can happen, or so some movies have suggested, and a vampire remembers its past life, and really has nothing to obstruct its human behaviors besides its physical disposition.
So, if the undead were real, I’m thinking the media and entertainment is a little more accurate on them than they are with things that are not related to humanity at all.