It's not a very unrealistic example--I've seen plenty of characters neglecting spot, while one or two party members put in max ranks and whatever else they can.
I think that it might make sense to give one PC a bonus (like, +10) to the check if another passed it. That would be "pointing the hidden foe out". It's still entirely possible for an unperceptive person to miss a well-hidden foe even after having them pointed out.