What is the trap you hate most?

[Mystical Jackal]

The one I hate most is PP-Zero Trap. Oh, how I hate it very very very much! It delinks my moves and ruins my strategy eventually.

[Rakurai]

It's a toss-up between PP Zero and Sludge traps for me.

Both can effectively end a run of a level 1 dungeon if they affect the wrong move or item.

[Chingchar]

Probably sludge or pitfall traps when Im running it doesn't work sometimes and my partner ends up falling ^^;

[Jacobthepokemonfreak]

I love Pitfall traps, since I normally go solo through a dungeon but I hate PP-zero traps like in those 99-floor dungeons!

[Orithan]

Out of what I've encountered in dungeons on standard missions, PP-Zero traps are the worst because they practically force you to bring several Max Elixirs and can completely ruin your day if you encounter several in one dungeon. I heard that there is an even worse trap, the Grudge Trap, lurking in Sky's Guildmaster rank dungeons.
For escorting clients, Warp Traps are the worst I ran into because they can (and often do) completely screw the mission up if you lack a Rollcall orb or something to get you to the client or the stairs quickly (and did I mention that you can not tell the client what to do). Though, I can imagine that the Pitfall traps are the very worst for these types of missions because I suspect that they result in an instant failure if the client steps on one.
In quicksave dungeons (Blue/Red Rescue Team), Sticky Traps can really screw you over if they take your last Apple or Escape Orb. I always bring Cleanse Orbs and/or No-Stick Cap into these dungeons to make sure that I can run if I get into trouble. Especially dangerous in Northwind Field because of the Perish Song Politoed that run around there. Sludge traps are not as bad because the resulting Grimy Food can still be eaten, but can be annoying if they take gummies.

[Mystical Jackal]

I love Pitfall traps, since I normally go solo through a dungeon but I hate PP-zero traps like in those 99-floor dungeons!

Pitfall Trap can be either good or bad depending whether you go up or downward the dungeon. If you're going up, it'll disturb you, but if you're going down, it helps!

Out of what I've encountered in dungeons on standard missions, PP-Zero traps are the worst because they practically force you to bring several Max Elixirs and can completely ruin your day if you encounter several in one dungeon. I heard that there is an even worse trap, the Grudge Trap, lurking in Sky's Guildmaster rank dungeons.
For escorting clients, Warp Traps are the worst I ran into because they can (and often do) completely screw the mission up if you lack a Rollcall orb or something to get you to the client or the stairs quickly (and did I mention that you can not tell the client what to do). Though, I can imagine that the Pitfall traps are the very worst for these types of missions because I suspect that they result in an instant failure if the client steps on one.
In quicksave dungeons (Blue/Red Rescue Team), Sticky Traps can really screw you over if they take your last Apple or Escape Orb. I always bring Cleanse Orbs and/or No-Stick Cap into these dungeons to make sure that I can run if I get into trouble. Especially dangerous in Northwind Field because of the Perish Song Politoed that run around there. Sludge traps are not as bad because the resulting Grimy Food can still be eaten, but can be annoying if they take gummies.

Wrap Traps are the worst in escorting jobs! As you said, it is always good to carry a Rollcall Orb on when you go escorting a Pokemon.

[spyro and sonic]

PP zero and Grudge.

[VaironGod]

PP-Zero, Sticky Trap (so annoying) and Explosion are the most annoying to me. I love having Psyduck in Blue Rescue Team since I already get to cut out Explosion traps.

[hawkmbl]

The PP zero trap...

*Remembers the torment of the regi cave in PMD Red

[ansem the wise]

PP-zero are annoying but the one i hate the most are the warp traps, with my team scattered im dead XD

[Dragontail]

PP zero and the sticky item trap.

[Kutie Pie]

Skill Drop, Explosion/Self-Destruct switches, and Sludge are my biggest ones for me. Poison Sting if I have nothing on me.

[G50]

PP Zero and The Grimer-looking trap.

I use a scarf now to prevent traps from working, glad they put that in the games...

[AnonNekomata]

PP Zero, Grimy and Sticky.

I've also heard of this Grudge Trap now (although I haven't played EoS myself) and I think it sounds absolutely dreadful.

[Green Blockhead]

Monster Houses.

[jireh the provider]

Grudge trap. Oh the agony.

[Mystical Jackal]

PP-Zero is at the top of most hated trap. To be honest, I predicted that.

[Earth Wolf-Howl]

Personally, I hate the Sticky Traps, Warp Traps and Explosion traps.

Just out of curiosity, what are Grudge traps?

[Brew]

To be honest, it varies depending on the situation. For escorting jobs, warp traps are the bane of my existence. I really dislike the Pokemon Traps whenever there's an item of interest in the same room! Overall, I despise PP-Zero traps the most in any situation, period.

Just out of curiosity, what are Grudge traps?

The Grudge Trap is exclusive to PMD: EoS and is very rare. Here is a direct quote of its effects:

Warps all wild Pokémon around the Pokémon that triggered the trap and gives all wild Pokémon on the floor "grudge" status. This usually results in all power points being drained away. This trap is exclusive to certain dungeons in Pokémon Mystery Dungeon: Explorers of Sky, such as Destiny Tower and Inferno Cave.

Source: Bulbapedia

Monster Houses.

All of my rage.

[33Whimsicott33]

Grudge Traps are a major pain. IQ skills for the Regular attack really helped with those.