So ash shell is kind of a goofy spell. If you cast it on someone without any witnesses (unless they were already hostile) they will not attack you when they "wake up". I was playing around in Tel Mithryn last night when I discovered an exploit for this quirky mechanic. If you ash shell someone from stealth (no witnesses) and crouch near their body spamming "pickpocket" there is a brief window of time where you can access there inventory before they start the wake up animation. Any pickpocketing that happens during this time is not reported, you cannot be caught and you automatically succeed. However, it does not appear to increase your pickpocketing level. When they wake up from the ash shell they may say something hostile but they will not attack.
I imagine this glitch may have already existed in another forum, but ash shell seems to work incredibly well for this. I robbed Neloth blind XD