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: Potentially any enemy in SOF2 on Consultant and Soldier of Fortune difficulties, due to the AI being a cheating bastard with accuracy (they have pixel-perfect aim at very long range, while you are screwed by recoil), visibility (they can see you through thick brush, smoke, and fog, and even behind hills), and grenade timing (sometimes they will telekinetically detonate it in midair).
"Funny Aneurysm" Moment: One of the levels has Saddam Hussein in it (he only appears in a cutscene), through cheats however, you can spawn and kill him. Now try to play this game now that Saddam is dead for real.
Narm: Most of the dialogue and voice-acting in Payback is so ridiculous and over-the-top that it's almost impossible to take seriously.
Some of the death sounds from the first game, especially when Mooks got burned.
Nightmare Fuel: The slaughterhouse in the Sudan mission in the first game.
Sequelitis: The third game. No John Mullins, different developer, different story.
That One Boss: The final boss of the first game is regarded as this by many, with an extremely powerful weapon, nasty turret back-up and being absurdly resistant to everything with the Handwave of "he's wearing body armour".
The Interrogator in the Hong Kong prison in the second game, with his near-instant-death machine gun. And he's Made of Iron even though he doesn't wear armor.
The Final Boss in the second game is an attack chopper that rip you apart in seconds and takes an INSANE amount of ammo to bring down, this is the one time where the OICW actually comes in handy, as if you can adjust the range properly, you can lob grenades at it safely and defeat much faster then you would with the normal ammo.