We all have our stories of retarded dwarves, here's one of mine.
A giant wave of useless cheesemakers come to my fortress and I assign them to fortress guard since I didn't have any. Ignis promptly starts to spar and get a punctured lung. Instead of being a good wounded dwarf and staying in bed, he promptly walks around the fortress falling unconscious, refusing any medical care whatsoever. This I could tolerate because it meant the idiot would be dead soon and no one would care. After traveling to my royal dining hall in just under a year, he proceeds to grab a plump helmet stew from my nearby food stockpile. He then promptly falls unconscious again and drops his food in the hallway. The stew proceeds to rot and create a gigantic amount of miasma and there is nothing my dwarves can do about it since the stew is owned by Ignis. After waking up half a season later, Ignis, seeing his stew has rotted, proceeds to the stockpile once again to grab some cat biscuits. You can see where I am going with this.
For 2 years I deal with this before realizing why I had so many unhappy dwarves and gigantic miasma clouds.
Finally Ignis dies after 5 years of making my dwarves miserable. I dump his body under a drawbridge and set the nearby lever to repeat. I want to make sure the molecules of Ignis do not spread through the air and infect anyone.