As DM I use initiative cards that have some basic skills/stats/figures for the PCs, so I know what their skills are. I would run a “room encounter” something like this:
First describe what they see when they walk in (I assume a “take 10” on a Spot check, in this case no one was high enough to notice anything “odd” or “standing out”) “The room is roughly 10 paces by 10 paces and contains a desk and chair in the middle of the room; on the desk are numerous papers and an inkwell with a quill in it. On the wall directly in front of you is a bookcase holding books and various other objects. It is currently lit by a 5 candle, candelabra. As you move into the room you notice there are no windows and a rug covers the middle of the floor directly under the desk.”
If a character states that he walks over to the desk to search through the papers (this time I assume a “take 10” on his Search check because nothing is technically hidden, and he is successful) “You find a journal mixed in with the papers.” Now I know that there is a false bottom to the single drawer in the desk. If a PC just “searches the desk” the DC to find the false bottom and mechanism to open it is 30 because it is excellent construction. If the PC says he searches the drawer for a secret compartment I make the DC 25 because he was a bit more specific. If the PC is very specific and says I search the drawer to see if there is a false bottom, I give him a +2 competence bonus on his roll for “being thorough”.
Another character walks over to the bookcase to get a closer look (it is the rogue PC). When he gets over to it I again assume a “take 10” on his Search because he is causally looking it over but his check is successful and so…”The books are not part of a set as they are all of different sizes and covers and they do not look like they have been used in a while because a thin layer of dust on and around them seems undisturbed. You also notice that an unlit candle leans slightly at an angle towards the back of the case.” Now I know that the candle is an unlocking mechanism for the bookcase which is actually a concealed door. The mechanism is not really that masterful so if the PC just states that he searches the bookcase for secret compartments, etc. the DC is 25 to find it. If on the other hand he catches on to the clue I gave him about the candle and checks to see if it moves, the DC is only 20 because he is specifically checking out the candle.
There also happens to be a small, well hidden compartment under the rug in the middle of the room. If the PCs state they are searching the room the DC is 35, because there is no way they would see it without the rug being moved. If someone states they are looking under the rug the DC drops to 25 (because it is still difficult to notice, but not impossible). This compartment is also trapped and unless the rogue checks it out, someone will probably set it off. If the rogue looks at it, but does not specifically state he is looking for traps I again assume a “take 10” so that he has some chance of noticing it (he would have failed in this case) but if he says he searches for traps and rolls at least a 14 he will be able to find the trap.
Sorry about the length of this. Hope it is of some use to you.
Happy Gaming!