iserith
Magic Wordsmith
Well yeah, there's that, too.
which is another strike against PP vs static DC for me. If I've described a likely trap and the players ignore it and soldier on through the kill zone, the players' obliviousness is also the character's.
It's still fair though in my view because the player has made two informed decisions to get to that point. The first decision was what general task the character is doing while traveling the adventure location ("keeping watch for hidden danger"). The second decision was to do anything other than investigate the clue. So I can sleep easy knowing that I set up a fair situation and, of course, have pleasant dreams about any subsequent character deaths that occurred.
But then, I try not to use conventional traps. Rather doing things like in Raiders of the Lost Ark, where the players know that boulder is coming loose, but they really really want that idol - let's see if their plan works! And if not, we get a chase scene.
That's my preference too. There's only so much awesome you can wring out of pit trap covered with a painted canvas, you know?
I'm also not inclined to use ambushes. When I have used them, it's been like an ambush from an episode of Hercules, where Kevin Sorbo and Jester Iolus are mugged by school students in disguise at the start of the episode: Just a fun little fight to amuse the audience and introduce this week's antagonists, but nothing that makes the good guys sweat. So missing out on a round of action because you didn't see it coming really won't hurt.
So I recommended not worrying about your Perception score if I'm ever DMing. It's not a priority for my style.
When I kill a PC, I want them to see it coming.
It's pretty rare for ambushes to occur in my game as well.