The suspicion bar in pickpocketing doesn't seem to ever go down on a handful of characters. I tried searching for earlier posts about this, and found this thread from two years ago:
http://underrail.com/forums/index.php?topic=1590.msg9121It doesn't seem to work for global characters (those that move around in the world). I'll check it out when I get the time.
This seems to match what I am experiencing. Is this still an open issue?