Probably for most of the clean up mobs. If his inventory is full, he keeps trying to pick up things which gives the echo that he is picking it up. Makes for a minor bit of a spam. Might want to change the check on his inventory to before he picks up stuff or change the echo to saying he tries to pick up some trash and fails. I suppose if you got really fancy, they could go to the dump when their inventory is full and drop everything. That might be kind of interesting after a long time up.