Someone on G+ asked:
"Mechanically, why were players expected to role play 'finding traps' but the X in 6 chance to find secret/hidden doors has been there since the get go?"
We need to distinguish between finding traps and disarming/circumventing traps. The accepted practice is to role play disarming/circumventing traps, but that's not the usual case for finding traps.
Characters find pit traps, for example, by falling in them, as determined with the roll of a die. The Underworld & Wilderness Adventures says on page 9:
"Traps are usually sprung by a roll of a 1 or a 2 when any character passes over or by them. Pits will open in the same manner."
Once players know the pit is there, it's easy to avoid in the future. We might be tempted to complain that dice rolling of this sort is unfair in its arbitrariness, but consider the alternative of role playing the examination every crack, hole, and loose stone in the dungeon.
Other kinds of traps — where the presence of a trap is obvious, but the way of avoiding it is not — we resolve through role playing. "You enter a room with a rotting bisected goblin corpse in its center. A few feet from the goblin's body, an overturned bucket spills grease onto the stone floor. Above the corpse, you notice a dark slot in the ceiling from one side wall to the other, and connecting grooves running down the side walls that seem to be greased. What do you do?" No dice roll required.
What about rolling for secret doors? Here's U&WA again:
"Secret passages will be located on the roll of a 1 or a 2 (on a six-sided die) by men, dwarves or hobbits. Elves will be able to locate them on a roll of 1-4. At the referee's option, Elves may be allowed the chance to sense any secret door they pass, a 1 or a 2 indicating that they become aware that something is there."
The text uses "located" rather than "opened", and draws a distinction between actively locating known/suspected secret doors and passively spotting unknown/unsuspected ones.
That suggests a procedure where, after a secret door is located by a roll, we role play opening the door. "I'm going to try pushing each edge of the door outline, and if that doesn't work I'll fiddle with the nearby sconce."
The mechanics for traps and doors are the same (with the obvious reversal that traps are meant to be found (triggered) and secret doors are not).
How to Open the Secret Door
- Push door edge to pivot door.
- Twist wall sconce near door.
- Pull out jutting stone near door edge to release latch.
- Replace missing wall stone lying among debris on floor (falls out after door closes again).
- Only opens for [1-2 Magic-users 3-4 Fighting-men 5-6 Clerics].
- Only opens for [1-2 Monsters 3-4 Undead 5-6 Puddings, jellies, etc.].
- Push two stones, one on either side of the door, simultaneously.
- Smear you hand with blood, and touch the faint brownish handprint in the middle of the door.
- Step on protruding flagstone on floor.
- Drain water from adjoining room to relieve pressure on door.
- Burn away wax facade.
- Opens when the other door to the room is locked.
- Hidden door is a decoy; entire wall rotates.
- Insert staff or rod in small hole to lever door open.
- A strong magnet raises a latch internal to the door.
- Opens in light of the moon (may require several mirrors).
- Circular door. It unscrews.
- Prying the base of the "door" unfolds a ladder — there's a trap door in the ceiling.
- Pull latch inside mouth of stone devil face.
- Rearming nearby trap causes door to open
"Somethings" Elves Sense Besides Secret Doors
- An elf died on this spot centuries ago. Clerics able to cast Speak with Dead may contact this elf regardless of their level and how long ago the elf died, although the spirit mostly wants to share the morbid elven verse its been composing to while away the years.
- Cold iron
- Flowing water
- Elf needs food