These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
For that matter, the scenes where we don't see the demon but rather the effect it's having on the world, like the smoking hoofprints in the forest being left by something we can't even see, are VERY effective.