Picture the scene.
You crack open the fridge, fumble past the leftovers and (hurrah!) locate that jar of mustard that you could have sworn was half-full. Only those deceptive splodges clinging to the sides of the jar are little more than a masquerade of thin smears and (boo!) the jar is, in fact, devoid of any appreciable content.
Where once there was mustard, now there is only disappointment.