So I guess a Cleared area isn't really a cleared area?

I just fast traveled to a bandit camp I took out earlier. The map said it was cleared. Well I popped in and ... was immediately attacked by a band of ... bandits. What made if even funnier was that as soon as the fight started a blood dragon came in and took out the band ... of bandits.

Anyway, can I assume then the Cleared, when mentioned on the map, only means that I have cleared it once and have taken any unique items that were there? The place still respawns and gets new creatures and random loot?

correct.

Yes. I have also heard conflicting things on whether clearing a dungeon level locks the dungeon or resets the level of the dungeon. I would to know if someone could clarify that.

I run into this myself, fast traveled to a cleared out outdoor location and it was filled with bandits and yes a dragon joined the party.

I heard the same about the level lock. I had first gone to this camp at a very low level. The band of bandits were all roasted in one blast so I assume they were still pretty weak (man that was fun to watch). I was level 20 at the time so I'm pretty sure the bandits were not my level.

Man, if that's the case I should have done a whole lot more dungeon delving earlier in the game

I don't know how the mechanics work in this game, but things like Fallout 3 would basically make it so that whichever areas you first visit when you are a low level would permanently be low-leveled, so that you could always go back and have fun sniping the skulls off of raiders, while the fringe areas you don't explore until very late become very threatening.

In Oblivion, where the randomized chests were part of the main goal, the fact that they always respawned, although the things like welkynd stones didn't, was part of why people would pick up favorite dungeons. Every three days, you could go back to the same vampire caves and fight a new batch of vampires and loot a new batch of treasure chests.

Some areas are marked as "cleared" when leaving; however, there are other areas that I am sure are completely clear, but do not get that designation. At first I thought the "cleared" marking would allow me to "cross locations off the list" as I travel, but it seem inconsistent. What do you have to do to make a place clear - kill everything, loot all chests, check all bags?

I'm not too sure on how long it takes for respawn, but I have heard that respawned locations after such a duration will also not be locked at the level previous and scale up to provide challenge.