From Ultima Codex
Ultima Online which is absolutely essential for an aspiring Thief. It allows the player look into the inventory (meaning player and NPC backpacks and pack animals) of others. Since breaking the privacy of someone like this is considered unvirtuous -while not a definite crime- the act alone lowers the karma. This means that the skill must be learned if the skill Stealing is supposed to be of any use, as without it, the thief can only steal random items, instead of something specific.
There are not many tips training this skill, as most is just using it. However, one good tactic is to target unattended pack animals, as with no player near by, they are easy targets for Snooping.