I've been experimenting a fair bit with... let's call it, "reducing the chance of future spinal issues due to excess load" of various townsfolk. While engaging in this public-health improvement activity, I've noticed that while my pickpocket chances for most items are perfectly stable, anytime an NPC is carrying large amount of gold (over 1000), the rules for relieving them of their gold stash seem to become truly bizarre and unstable.
Target: Giraud Gemane, Solitude Bardic College
Light Fingers: rank 2 (+40% bonus)
Cutpurse: Yes (+50% bonus)
Attempt 1: No gear
Displayed success chance: 15%
Attempt 2: Closed pickpocket window, reopened without changing anything or either character moving.
Displayed success chance: 65%
Attempt 3: Closed window, equipped Fine Boots enchanted with +40% pickpocket
Displayed success chance: 55%
Attempt 4: Closed window, reopened; still have boots equipped.
Displayed success chance: 5%
Attempt 5: Closed window, equipped Gloves enchanted with +40% pickpocket bonus.
Displayed success chance: 0%
From tinkering around a lot with different NPCs and gold amounts it feels like every time I open the pickpocket window, I will either get a "good" base pickpocket chance of 65% or a "bad" base pickpocket chance of 15%. From there, every pickpocket bonus item I equip actually reduces my chance of success by about 10%.
Again, this only appears to kick in for NPCs with over 1000-ish gold. Under that amount, I have a 90% success chance every single time regardless of equipment.
Can anyone offer an explanation for this behavior, or is this a bizarre bug of some kind?