seriously.. went through bleak falls barrow for like the 20th time and there was more junk lying around than there were enemies O_o is this a bug? or is it like that for YOU aswell?
Multiple issues here, dungeons has an respawn rate of 30 days, returning before this might or might not reset the reset counter but anyway 30 days is minimum.
Second is that dungeon reset is simply that all object who belong to the dungeon is reset, monster bandits even the junk is removed and new is placed, random and level scaled things are recalculated.
However if you drop something, even pick up an axe and then drop it, it belong to you not the dungeon so it will not be affected by the reset. I you place anything in a body or an container it will disappear. This is done as it's simpler to just remove all objects related to the dungeon and replace it than rebuilding the scene.
Yes it causes save bloat but main reason is that ash piles are also not in this dungeon list, the same for some weapons enemies drop.