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.
Demonic Spiders: The Hoverbots. While there are only 2 enemies in the game, them and the turrets, they tend to charge the player while moving insanely fast and crazily. This makes them nearly impossible to hit if your life depends on it. Even with the mod that gives you a .45 Tommy gun, a Remington shotgun, and a high-powered bolt action sniper rifle, their rotors are damned indestructible and they're nigh-unshootable when they charge at you full tilt, out of nowhere.
And even if you do land hits on it while it charges at you, they most likely won't be lethal enough to take it out (not hitting its two weak points), or not enough bullets will be planted in the thing before it goes out. Although, using the Glock's auto-fire, it can be killed with ease, but at a large cost.
Their only real weakness relative to the turret is that they rotate more slowly. If you see the light from the camera scan past a doorway, for example, you have significantly more time to step out from cover, aim, and fire before it sees you than with a turret.