If you think you'd know if a skilled pickpocket was taking your watch, wallet, or cell phone, think again. That's the lesson I've learned from watching a video of theatrical pickpocket (meaning, a legal "stealer") Apollo Robbins.
I've watched the video several times, I'm so fascinated by Robbins. His physical skills are amazing, but its the smoothness of his whole persona that is particularly impressive. Without that, his pickpocketing would be much less successful.
Have a look. And a read, if you click on that link.