Li Shenron said:
I say again that for my tastes there is enough uncertainty in (1) the character occasionally (but not usually) not searching in the right place, and (2) the group finding but not managing to bypass the trap.
Well, realistically speaking, the DM is in absolute control over whether or not a trap can be found, and whether or not a found trap can be bypassed. He or she must simply set the DCs for the desired result. Moreover, by means of description the DM greatly influences where the players search for traps.
That said, Take 20 means that, if a task can be done, it will be done. There is no doubt whatsoever. If you Take 20 and do not find the trap, there is no way that the trap can be found by you. Should the trap most often be found? Sure. In fact, the idea of "Take approximately 20" allows for traps that can be found most (but not all) of the time without the DM making a decision as to which traps cannot be found during adventure creation.
As a side note, if you are certain that a trap should be there, yet you are unable to find a trap, logic would indicate that you assume a trap you could not find is there. Not finding the trap does not prevent you from trying to trigger the trap through various means, such as the use of a pole or summoned creature. Finally, magic can reveal a trap that the rogue missed but you are certain exists.
As I previously stated, and as Silmarillius concurred, the problem is not the existence of traps, but rather the existence of poorly thought-out adventure designs. Adding traps without rhyme or reason is certainly no better than using a "wandering damage table." Conversely, placing traps (both natural and not) where appropriate to an adventure can heighten tension and increase the fun players experience. In one of the examples Silmarillius mentions, after one member of the party fell victim to a natural "trap" caused by rotten floorboards, they were able to make use of the trap area to defeat a construct that would otherwise have been a difficult fight for them (they earlier defeated a construct in a similar manner -- by bullrushing it into an underground lake).
Here are some other examples of traps, natural and otherwise:
Lakelands Campaign Logs said:
Hrum stepped out to look to the right. The passage sloped suddenly and steeply, and he lost his footing on the slick stone. His sword dropped with a clatter, waking some bats and sending them flying about. He slid into a wide chamber, where he managed to catch himself against an even steeper slope. He looked around at the chamber, and saw that it was some thirty-five feet across and twenty-five feet wide, but the area in front of him was a slick ledge maybe five or ten feet wide with a twenty-five degree slope. He could hear the steady trickle of water in a pool more than ten feet below. Hrum got shakily to his feet, trying to keep his balance.
The dwarf sent his raven up the other passage, but it ended in a cul-de-sac. He jogged down the passage quickly to check the raven’s report, and saw another camber, fifteen feet wide and twenty feet deep. The area was some fifteen feet high. Water had carved a sinkhole through the stone from the surface. The sinkhole formed a chimney leading out of the caves, entering the room near the far wall. It was the source of the trickling water in the area. Had they meant to exit the caves, it might have been a good find, but they would never find Brand Oarsman if they left now. He jogged back to tell the group the disappointing news.
When Desu tried to join Hrum in the slick-floored cavern, he lost his footing and went shooting over the edge. Bats, which had been roosting on the ceiling, flew around, disturbed, and chanced to put out the group’s torch. Luckily, however, they could not put out the magical light the dwarf’s raven was carrying. Desu slid and dropped fifteen feet into the brackish water with a huge splash that echoed loudly throughout the caverns. The water was deep enough that Desu took no injury from his fall, but as he struggled to make it to the surface, he took in water that he knew was not safe to drink. It was the least of his worries. Barely able to tread water, he broke to surface enough to gasp out a cry for help before the weight of his equipment pulled him under again.
Lakelands Campaign Logs said:
“Later,” Desu said. “We must conserve our strength for what lies ahead. And our time grows short.”
“Very well,” Darwin said, pushing past the webs into the ten-foot diameter passage, Locke close behind him. It was difficult to see far down the passage, choked as it was with old cobwebs. Dusty bones and dried carcasses lay along the floor, or were caught up in the webs, though none of them seemed recent. Looking at the bones, Darwin saw that humanoid bones were among them – some almost certainly kobold, and others human. As he paused to look, he could hear faint chanting from somewhere ahead.
Darwin pushed confidently down the corridor, but the old webs hid a pit. Both he and Locke fell in, dropping ten feet. Once they were out of the pit on the far side, the remainder of the party carefully walked around its edges. The entire group continued, now more cautiously.
Lakelands Campaign Logs said:
It was soon apparent what had happened to the escaped prisoner – Hrum walked into a razor-thin strand of webbing strung across the passage at neck height. Luckily, he was able to pull back before he was sliced too deeply. Clearly, the man-at-arms who had escaped had not been so lucky.
“I wonder why it didn’t get me,” pondered Darwin. “Perhaps, this time, my height was to my advantage!”
They cut the webline and went on. After another fifty feet or so, they came to a jag in the passageway that blocked visibility. Rounding it, they could see the sky through a thin veil of vines some thirty feet ahead. Once more as they moved forward, Hrum felt a razor-thin line cut into his throat. This time, he was barely able to stop before the cut became lethal.
Darwin raised his blade and ran out into the sunlight, determined to cut any lines that remained. They had rescued Brand Oarsmen, and brought him safely from the Dragon’s Lair. And they had survived.
Note that none of these traps were lethal in-and-of-themselves (Hrum, even after the battle, makes one save and fails one save, and still survives). Note that they make sense for where they are (none is "wandering damage"). Note that the webline traps do not even require a Disable Device check to deal with -- just a determined dwarf with a sword. And they certainly enhanced the game for the players, if only by increasing the sense of travelling through a dangerous environment.
RC