After searching for a bit, I couldn't find anyone else talking about this. Very often I will sneak, and the instant hidden appears, it is immediately replaced by full detection. When there is apparently no possible source for that detection. Very often when I pickpocket I will have to shimmy back and forth between positions to get rid of (Aware), often I have to to silly things like stand practically inside the NPC. This happens as much on my level 4 pickpocket as a fresh character, and as much on my medium armor char with the sneak passive as without.
What's wrong. Am I doing it wrong, and if so, how do I do it better, or are there just bugs? Do you just randomly get detected from behind? Is the NPC's model not making it obvious where "behind" is?