Enemies in combat picking up things

I've noticed it quite often. While there are hostiles nearby (either me or another NPC), enemies will waste time picking up stuff from the ground.

For example, in a recent fight against four drow mages, as soon as I killed one, one of the others started to pick up his potions and spellbooks, ignoring me.

Now, if this happened sometimes, that's fine, it adds more color to the dungeon "simulating" a greedy idiot, but not as ofter as it happens.