Let's say you steal an item from a persons house, but nobody saw you. Will you get attacked?
If you manage to leave town and drop the item in the wilderness and return to town (with no stolen property), will you get attacked or will you hear that someone got robbed and they don't know who did it?

nope, I wish the AI is that smart, but nope!

Well I didn't get a bounty when I stole something when nobody saw me go in and no one was in the house. Maybe mine was glitch then?

As long as nobody saw you stealing the item, nobody is gonna attack you.

The item however will be labeled "stolen" and can only be sold to thieves guild fences. The exception would be if you had that perk in "speech", that allows you to sell stolen goods to regular merchands.

Items labeled "stolen" will also be taken from you by any guard if you commit a crime and they actually catch you (even if it's completely unrelated to your theft).