I'm having a similar problem with stuff thats stuck in my traps. I'm thinking it might be a problem with ambiguity as to what is considered to be "outside." But basically theres goblin clothes and armour, and stones that are stuck in my entrance way that the dwarves refuse to touch. I've set them to be dumped, and played with every refuse option and dumping option I can find but they will not move them. I've also set the traps for removal but it just won't happen. Any clues?
As far as I can tell, "outside" simply means tiles that are not naturally subterranean. If, for example, you would channel away one tile of roof on the top floor, there would be sunlight coming in making it "Light, above ground", even when building a new roof above it. Constructed roofs can never change if a tile is above ground or not. The problem with dwarves leaving stones in the doors seems to be this:
1. I mark stones for dumping inside, and make a dumping zone outside.
2. Dwarves grab stones and start going to the dumping zone.
3. In the doorway, the dwarf suddenly feels the irresistable urge to eat, sleep, drink and go on break. He/she drops the stone.
4. The doorway was built on a tile that is not subterranean, which means that there's now a stone lying in sunlight, and that counts as outside. The original dumping dwarf will not resume the task, therefore the stone will be there until I turn on "gather refuse outside", at which point everyone will be busy RUSHING towards the chasm where there's cat paws or whatever.
My solution is to always have my dumping zones and refuse stockpiles inside, and when I need to turn on "gather refuse outside", I activate the military and babysit all my dwarves because there is NOTHING more deadly than allowing a dwarf to go wherever he wants.
The good thing is that miasma will not be generated on outside tiles, and even bones will disappear eventually. But stones block the doors foreverandeverandever