Do corpses disappear after a while?
When I...
- kill someone in a city, enter a house and leave a house OR
- kill someone in a dungeon, leave the dungeon and enter the dungeon
... will the bodies of the dead people disappear or can I still come back to loot them?
Bodies do not persist forever. Eventually they will be removed.
I was just beginning to think that the dragon skeleton at the College would be around forever, but when I visited it now it was gone.
Similarly, when I killed Belethor, I was surprised to see that his body had been cleaned up rather quickly.
Corpses tend to stay around longer than you would ever have need for them (I presume to give you adequate chance to loot), but they do disappear eventually, no matter their source.