There may also be another psychological aspect at play here, as well: put a new head on a high end drum and someone may think it's a lemon (ie. never been or can't be played) or possibly stolen, but keep the old heads on it and someone may think the seller has outgrown the sound or really needs the money (ie. regardless of the reason for selling, it's still a good instrument).
Though for me the psychological aspect is, "This is a guy who hasn't taken care of his stuff or maybe it is possibly stolen, otherwise why wouldn't they change the head?" Maybe the best compromise is to have a slightly used head on there, not one that is beat to hell or brand new.