So I went back to Geirmud's Hall by Ivarstead because I remember I had to drop some nice loot for being over-encumbered. I cleared this dungeon a week or so ago and went back only to find all the traps reset, all the doors relocked, and even the dungeon boss fought me again (jumping up out of his tomb or whatever). Shoot, even some of my loot was still lying on the ground where I dropped it.
The dungeon says "cleared" on my map so what's going on?
I like that map let's you know that you actually cleared the dungeon, but it doesn't surprise me that it respawns. I notice, in Geirmund's barrow, for example, that there was less basepop than originally (or at least it seemed that way to me) and although there was a high level mob at the end, it was not the named boss I fought in the dungeon originally, just a generic deathlord level mob. I am not sure on the timing for repopping a dungeon though - seems longer than three days.
I think the cleared info is useful, so you know you covered all ground - if you want to harvest stuff, you can always go back at some point, but I like knowing that I hit every room in a ruin or dungeon.