Well, opinions? I think this strat is legitimite, bordering on exploit, and gives something unique to the thief. I only wish that the thief's other trees were made more useful: diplomatic resolutions to quests, ability to talk sapient factions friendly or passive (e.g talk your way into a bandit clan) with Speech, regenerating safes and strongboxes and hidden merchant's chests with master locks for Lockpicking, acrobatics skill, etc.

If you're playing a thief character and you just paid someone for some training, than you know for a fact that person has money (and possibly a lot). Easy mark. This is just being smart. Why spend time looking for another person to pickpocket?

People don't carry much gold or jewelry, and if they do it's all [censored] garnets.

this
if you are a thief it's just being smart.
I can't imagine a warrior or a mage do that

Easiest way to do it is train up pickpocket till you aroun 60 to 70, then reverse pickpocket expensive items and then pickpocket them back, and repeat.