This was an extremely annoying thing that came along with the use of Energy Weapons in F3 and its back again in FNV. Basically if you turn anything into a Goo/Ash pile that pile will be there for the rest of the game. If its a respawning enemy the inventory on the Goo/Ash will be linked with the living enemy. I regularly go to a certain place to round up some dog meat to cook into dog steaks. Once I went there with a Plasma weapon and now there are 5 Goo piles that arnt despawning.
I wanted to try out Energy Weapons in FNV but I didnt for a long time because I had a large suspicion this problem was still around. I dont want to open the console to remove all these Goo/Ash piles every time.