I have witnessed a couple of courtesy clerks at some supermarkets who will take their finger and lick it in order to separate the plastic bags that are piled up together. I sometimes will grab the bag and I can feel the wetness of that person's saliva on the edge of that bag. I think it is unsanitary and the store manager should warn them from doing this practice. If one of them has a cold, and the shopper then touches the bag, most likely he/she will catch that cold.