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.
Most Annoying Sound: The moment before an orbital strike hits the ground, usually right on top of your entire team. You can't even run. Also, the announcer in skirmish, particularly on large contested map with lots of control points being hacked by both sides.
Nightmare Fuel: The Uprising patch gave the game a massive overhaul. CCP decided that just greyscaling the screen and playing a single descending string note wasn't enough to signify death, though: That single note got much louder, and if you leave the respawn cursor on your corpse icon (a skull and crossbones) and hit X to 'Call For Help', a heartbeat starts sounding, and if someone doesn't use a Nanite Injector on you, the heartbeat slows down. Now think about what's going through the merc's head the entire time this is going on...
Annoyance, most likely, seeing as how they have an implant that resleeves them in another body as soon as they die. For them, death is an inconvenience that just happens to be extraordinarily unpleasant.