Black Knight Irios
Explorer
From the same initial premise I took a different solution and ruled that *anyone* can find a trap with any DC that they can make. If a fighter puts all his skill points cross-class into search, I'd let him search for traps. Why have a situation that *requires* a rogue in a party, that *nobody* else will do?
Perhaps the Track ability is a good indicator, and make Trapfinding a feat which is available to all characters (as well as being automatic for 1st Rogues). This then puts it on exactly the same footing as tracking for rangers (except that it is a far more necessary ability, of course).
But making the Trapfinding ability available for other classes, makes it less special and makes the rogue class weaker.
If I allow everyone to cast spells it is nothing special anymore, an extreme version of your doing.
So getting back to the example -- if a guard just says he looks at the potential spy and takes 20 on his search check, you're saying you'd give him what DC to find the notes? Or would it be impossible? Whereas if he cut open the scabbard, you'd give him what DC to find the notes? Or would it be automatic?
First is the observed person moving, if he is an the guard keeps his square he can't T20 at all because the observed one leaves 10ft. after/within the first round of movement.
If the observed one is standing right in front of the guard for 20 rounds and the guard T20 for search without touching anything by just looking or smelling or what ever, I would say increase the DC by 20 it's like hiding when running, so the DC is now 30, it is not very easy to find it now, especially without using T20 at all.
But that fact I think is already included in the Trapfinding DCs, therefore you should not make it harder for rogues to find traps or make it impossible or call it whatever you like.