Though I mostly steal gold and not items from the vendors. I'm not that keen on implementing a system similar to The Elder Scrolls where items are flagged as stolen whether or not you're seen stealing those items.
Sure, if you steal a unique, powerful and recognizable item then I can understand it. But when the pewter goblet and tinder box that you pilfered from an inn at the other side of the ocean is instantly reconized as stolen loot it's just ridiculous.