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.
YMMV: Respawn of the Dead
Cargo Ship: Soldier and his Shovel, taken to the furthest extreme possible when he has sex with it.
Complete Monster: RED Spy. Not only was he plotting the deaths of his own team, part of the plan including successfully talking Heavy into sacrificing himself for Medic's sake as well as later locking Pyro and Medic in a room with a horde of vicious zombies, but he actually suggested that Engineer helped him RAPE Sniper before he killed him.
Hilarious in Hindsight: This fanfic was written before the "Scream Fortress" update, which introduced several cosmetic items that make players look like zombies and the Harder Than Hard "Caliginous Caper" Mann Vs. Machine mission, which replaces the robots with armed zombies.
Heavy stuck in the fence has become a very recognizable image in a large part Team Fortress 2 fandom. There's a lot of Black Comedy fanart interpretations out there.
Moral Event Horizon: Spy crosses this when he agrees to RED and BLU's orders to slaughter his own teammates.
Narm: It's a bit inappropriately amusing when Medic says, “Nein, nein, nein, nein, nein…”the second time Heavy gets stuck in the fence? But you'll stop laughing pretty quickly...
It was pretty creepy when the Soldier's shovel started to talk to him...but it's just hilarious when the Soldier has sex with it. Firstly, the situation is so ridiculous that it barrels through squick and ends up Crossing the Line Twice, and secondly, how is it even possible to have sex with a shovel?!
Squick: Anything involving zombies eating, Soldier getting it on with Shovel. Literally.
From the prequel: Spy's unique uses of the masking technology.
While there's nothing wrong with Heavy and Medic having sex, something is very offsettling about them having sex in front of Stumpy.
And as for the prequel, it is every person's prerogative to make up their own mind whether they think scalpels belong in the bedroom...
The detailed description of Demo's empty eye socket in the prequel is a little disturbing. Let's just say that Heavy is one of the few things Medic likes that aren't squick.
Tear Jerker: Many parts, but most notably the abandonment of Heavy. His last dialogue exchange with Medic, Medic's subsequent freakout, and Heroic BSOD only drive it home.
You can tell who's read this story by whether or not the mention of Venice makes them choke up.
BLU Spy succumbing to zombification.
"And then he was home."
If Pyro's eventual death from the virus didn't tug at something, you may be as souless as some people see him.