I'm laying out a few traps in a dungeon my group is heading into and I haven't really be able to come to a conclusion on how to handle the interaction with them. Specifically, are there mundane methods to hide a trap that make it harder to detect? For instance, I've heard of objects having Symbol of ------ inscribed on them and then covered with a cloth of some type. If someone removes the cloth, they can see the symbol and thus it activates. So since the trap itself is not actually visible when the cloth is over it, does it increase the DC of the Perception check to find it when searching for traps? This assumes the character can detect magical traps but does not have an automatic ability to just be alerted of traps like the Trap Spotter rogue talent.
My initial thoughts would be that it would affect the DC to detect the trap using just Perception, not unlike if you lacked darkvision and were searching for traps in the dark. It's not impossible, just harder.
How does everyone else handle magical traps that are hidden behind mundane objects? Or is this already covered in the rules somewhere that I've overlooked?