I'm sure they have accounted for such a contingency and when spawning anyone, anywhere, clutter probably spawns with them.
I was personally thinking a better, easier solution would be, looking at Morrowind (Oblivion too, but easier to see in Morrowind), There is a very dinstinct feel to the dungeons. Even dungeons of the same environmental type.
There could be Smuggler Dens, Outcast Mages, Necromancers and Vampyrs that take residence up in Caves.
If a quest target makes sense in a smuggler's context. They could spawn the smugglers in one of the static Smuggler caves (Maybe along with normal occupants, maybe not?), rather than actually spawn the clutter with them, save the target item.
From a suspension of disbelief perspective, the player has no real reason to believe these particular smugglers aren't in coohts with each other, even if you start a new game, and they turn up in a different one, the player can't logically make a connection that "Because they were here last time, they should be here this time" from that perspective. And from a design perspective, you maintain a semblance of control. You know these targets aren't going to be the proverbial "Fish out of water", and from a world-building or system designer standpoint, you don't have to worry about random object generation at every turn.