In no particular order;
1. Spawnkilling with a tank. This takes even less skill than using a plane, which I admit, does take some. Using a tank is cowardly, and just proves to me that you can't fly, and don't want to; so I simply return the favor.
2. Spawnkilling with a plane. It does take some skill, but excessive spawnkilling (any spawnkilling that doesn't cover your own bombing raid) is simply annoying, monotonous, and pointless.
3. Threats. I can handle idiots who cuss too much, I enjoy messing with them. They're almost always idiots my age who think you have to self-censor stuff that they spell wrong. People who make threats, on the other hand, are different. There's nothing funny about a threat unless you know the person it's coming from, and you know when they're being serious.
4. People who cuss too much and don't let me mess with them. That's when it's annoying. I can entertain everyone in the game and make the idiot quit when they play along, but not when they ignore it.
5. Teamkilling. Self defense, defense of a teammate, or shooting a spawnkiller or any other kind of general moron is different, I mean just shooting down a teammate because you can. I park my tank in front of these guys.
6. Teamkilling for revenge from a previous game. Picture this, okay? I shoot down "GuitarPick96", who is on the other team. I shoot him down a few more times. "ForkSauce42" bombs my last hanger, and I lose. New game. GuitarPick96 and I are on the same team. I take off. He takes off, and pumps a bunch of rounds into my tail, and says "That's for last game.". If it's an Aspirant, I'll explain that we were on seperate teams. I assume anyone else that does it to simply be stupid, if not for shooting me down, then for thinking I wouldn't return the favor, and that they could do anything about it.
7. Vulgar names. There's little kids here, do you really need to tell them what to do to themselves?
8. "Daddy's little girl". The people who can do no wrong, at least in their mind. That guy, Cody The Winner, who was
recently blacklisted, was teamkilling Wig. Three guesses what Wig did. Next game. "Wig's a teamkiller! The guy just started shooting me down!". Really? People like this suck. In real life, they suck. In Dogfight, they suck. There is no way to not want to hit daddy's little girl with a piano bench.
9. Walker on carrier. Maybe new guys don't know that they can't be seen, so it's just spawnkilling with limited ammo, but aces know that you can't see them. They do it anyway. Ridiculously stupid.
10. People who make long lists about what they hate, especially when the list is exactly nine points long.