looting time varies greatly depending on the target. All containers take at least a minor action to open, and that's if they are not tied shut, locked, etc. So you can see how it would be problematic to loot an adventurer lets say with a scroll case sealed in a coffer inside a backpack. Such things are best handled in non combat time. As a GM, I usually do have the loot keyed although sometimes I have a random roll for repeat enemies like minions and the like.

Thievery decreases looting time and you can nick a purse in most cases with a minor action assuming the target has one.

Some example base DCs

Minor actions - perception is move action
Looting a corpses purse 10
Looting a living target's purse 12+target's level (this is not pick pockets, it's searching an immobile living foe)

2 standard actions - perception is 2 full rounds.
Looting a corpse (rifling only) 15
Looting a living target immobile 17+target's level

5 standard actions - perception is 5 full rounds.
Looting a room (nothing locked just obvious stuff) 20
Looting a room under fire 22+highest active enemy's level. {Don't laugh it's been done}

Looting is based on either thievery(only trained) and perception. Those trained in thievery may make both rolls simultaneously.

Each full multiple of the time used up to 3X gives +1 to the roll.