Healers
- Not seeing healer DoTs active on targeted mobs when party health is good.
- Not seeing Regen active on tanks with non-critical, but non-full HP.
- Seeing spammed Cure/Physick on party members with damaging status effects, but not at critical HP.
- Healers who think they're DPS, waiting until tank 10% HP before switching off Cleric stance and panicking with very strong heals.
- Healers who heal DPS before healing themselves and die as a result.
- Healers who put Regen on full-HP tanks before they pull.
- Spamming Medica II and then blaming the tank for not holding aggro against that.
- Healers without cross-classed Cleric stance.
- Not carrying Echo Drops or knowing how to use them.
- Healers who do nothing in the name of conserving MP. Placing DoTs and Regen will conserve more MP than doing nothing at all and panicking when the tank is nearly dead.
DPS
- Using single-target attacks on unmarked mobs, ignoring the marked one and dragging aggro off tanks.
- Bards and summoners who spam normal attacks and don't have DoTs up.
- Dragoons who spam interrupt skills for additional damage on targets that actually need to be interrupted, resulting in stun immunity when it actually counts.
- Dealing ranged damage to mobs before tanks do.
- Standing in front of mobs to attack them, instead of the rear.
- Standing behind mobs known to have reararc AoE, even after the AoE already displayed several times.
- Activating dungeon mechanics in the middle of mob fights, even though healers with the lower DPS value should normally do this instead if party health is good.
- Monks who don't ever change their position - especially if that position happens to be in front of a mob's face.
- Melee DPS who don't use LB for fights that have obvious DPS checks in the middle of dungeons.
- Ranged DPS who stand in the path of wandering mobs, drawing pointless mobs into a fight.
- Ranged/Magic DPS who use LB the moment it is charged even though a fight has an obvious DPS check, and a melee DPS is available.
- Any DPS who waits until 10% to use a LB middungeon, sacrificing all the LB points that could have been earned after that.
- Summoners who use Titan in group content.
- DPS who use single target attacks against pulls of 4+ mobs.
- DPS who use multiple target attacks against single mobs/bosses.
- DPS who pull 8 additional mobs into a tank's 4 mob pull, and then complain the healer is incompetent in the resultant wipe. You don't decide how big the pull is, the tank does.
- Not using Goad on low-TP tanks and then complaining they can't hold aggro.
Tanks
- Standing around waiting for 4 seconds before every mob pull just to mark a target. Put it on a keybind and mark during the range pull's cooldown before your AoE.
- Standing around doing nothing with full TP.
- Dark Knights zeroing their MP repeatedly for no reason.
- Paladins using cover on a Dark Knight MT.
- Offtanks who never use Provoke to swap in.
- Any tank who doesn't use defensive cooldowns at all until they're at 20% HP, and then blasting all cooldowns at once. It reduces damage by a %, your defensive cooldowns are not healing skills.
- Warriors who use Berserk just before a boss invuln phase starts, instead of timing it to end when the boss invuln phase starts.
- Tanks who keep the tanking stance on nonstop even though DPS are obviously undergeared and will not steal aggro even if a DPS stance was used.
- Paladins who don't interrupt attacks that have 4s+ long telegraphs and very large AoE circles.
- Tanks who don't face the back of the mobs to the party. *Optimally, tanks should aim to spin the marked mobs about ~135-145 degrees so that DPS can swap between rear and flank attacks by moving just a little bit. Exceptions exist depending on how their AoE patterns are programmed.
- Pulling bosses when your party member is watching a cutscene. Bonus points if that party member is the healer.
- Warriors who don't use Storm's Eye.
All
- Standing in obvious AoE with very long telegraphs.
- Falling off platforms on their own without being pushed. Especially on Titan. Bonus points for blaming the healer for not reviving you after that.
- Using level 8-10 gear for any of the first 3 dungeons, when the Novice Hall gear is significantly better.
- Jumping to the start of the dungeon during a boss fight even though the healer is still alive and capable of hardcasting Revive.
- Not using health potions when you're at critical HP.
It's possible I'm just a very bitter person in that my gears get ground more than others' seem to, but it's also possible that my expectations are higher because I play every single class. The bold ones are the more frustrating ones.