Well, I cannot say it’s a frustrating activity, and yet there is a number of things worth mentioning :) In no particular order:
Ahn’Kiraj – Silithid Royalty doesn’t die like it should! Sometimes I need 5 natural resets before they give up and give me loot :) This bug trio is annoying!
Viscidus is nigh impossible to beat solo unless you’re a Frost DK, or scraping a dozen of specifically farmed items (something I’m not ready to do yet). Waiting for nerfs…
Make sure you run Blackwing Lair before Ahn’Kiraj – because goblin mobs there will drop Elementium Ingots. You need 6 to complete a couple of quests after C’Thun and get a number of weapon transmogs :)
Speaking of Blackwing Lair, the small dragon grounds are massively annoying to cross. Double that if you plan to go out to Blackrock Mountain. So God bless Bodhi Rana and his advice: after the last boss, queue a custom group, then quit it to teleport outside and to the nearest graveyard in 60 seconds!
Karazhan Chess Event is bugged, and it has as much as three of them! You can use </cancelaura Control Piece> macro in case a piece disappears (never happened to me though). You can talk to Medivh and reset the encounter to take off the Silence debuff after the game. The nastiest one is not solved: after you beat the event, the loot chest is not active, there’s no cog, and you can’t get loot or get it mailed to you after the dungeon. This one was not solved yet. Still, you can proceed to final boss.
Battle for Hyjal can be beaten easily, but it’s massively annoying for melee classes – because gargoyles and frost wyrms in the second part.
You need only one tower during Galakras encounter. Climb, clear, shoot him until Warlord Zaela “drops from the saddle”. Then just wait for him to attack you – may take a while.
Mantid boss in Siege of Orgrimmar is bugged! More often than not, Hisek will just stay on the platform and won’t go down. Pray he’s in the first group.
Archimonde in Hellfire Citadel is tricky on Mythic. He will heal to 50% when you go to Twisting Nether phase, and you’ll have to burn him down asap before he punches you flying to death. Barely scraped out my victory with a Holy Priest / 410 today after 3 attempts, and it required all possible buffs – intellect potion, rune, and food for Haste. Ofc, it will be easier for damage dealers, but all cooldowns should be saved for that phase.
Make sure you’re trying to overrun Lei Shen’s push at the longer platform edge, or else. The encounter is not wipe-safe :)
Make sure you’re blowing up Deathwing’s head armor pieces during Deathwing’s Spine! It’s something I double-check after my glorious half an hour spent, trying to blow up his ass armor plates :)
Wipe out all the existing trash in Molten Core – more often than not you will find set pieces in common mobs. In general, check the current raid’s set piece sources: if any of them says “world drop”, you should clear trash as a lawnmower.
Make sure to sell loot via Tundra Mammoth / Expedition Yak every time you have this opportunity. If short on bag space, take trash items (claws, eyes, goo etc.) and leave boss loot alone – it will be mailed to you afterwards!
Otherwise, older raids are a curb and stomp party :) Having fun with all classes!