A third class of monsters are the actual ‘creatures’ such as: Alien, werewolves, Predator (maybe), and giant mutated spider thingies.
Snakes: These like in Boa, Python, Anaconda, and Boa vs. Python only have a limited stance on their stealth. While quiet in a way, they are sort of clumsy. Massive sixty foot snakes are going to knock a few things over on the way to its victim. Rubbing against a tree would just knock it down. On a cliff (if it is above you), tumbling rocks are sort of obvious.
Oh and that hissing doesn’t work out either. If a starving snake is on the run… Well I’m no expert but snakes hiss as a warning. So they’re just telling the humans to go away! Secondly at this part; don’t stop and stare at the glory of a sixty foot snake. Just high-tail your ass out of there!
Another case would be the minions simply being incompetent. Maybe they just truly don’t know what their boss is doing or hiding. Whenever I can finally release Stride; you’ll see this example in the first bit of the story. Dave doesn’t have his prophet tagging along (she comes soon enough) so he doesn’t really know where the villain is. Intel is low in this particular case until later…
Supernatural Bad-Ass Who Won’t Die: Jason is the perfect example. Behind the mask is a mute. You never hear him coming. I’m sure you could smell him; because you know, death and water don’t mix. Well they do; but you get the point. Silent killers never expose their plans. Jason can never be figured out. Little virgin girl gets it (in understanding, not with an ax in the gutters, jeez.) Little virgin girl is always the hero anyway.
However Jason sort of cheats by the simple fact that he teleports; one moment he’s there and the next he’s somewhere else. Creep. Oh, Michael Myers! I can’t believe I forgot about him! He fits in with all of these silent types too.