I am susceptible to shopping cart envy.
If the cart of the lady in front of me contains healthier, less overtly branded, or more environmentally-friendly packaged foodstuffs than mine does, I turn a judging eye onto my own cart.
Do I really need cranberry juice? Soy milk in a non-recyclable carton? Store-bought whole grain cookies? How come my cart doesn't contain only fruit, vegetables, meat, eggs, dairy, and grains? Fruit juices are expensive and fattening. Soy milk comes in recyclable cartons in the refrigerated section. And I can bake my own cookies. And where's my cloth shopping bag?
And so, while the lady in front of me is checking out, I'm surreptitiously making sure the re-stockers earn their pay by stuffing the cookies under bags of M&Ms in the candy display.
On the other hand, if the cart behind me is stacked with boxes of soft drinks, Twizzlers, and Cocoa Puffs, I feel morally superior. What a rube! All that junk. Like you need that in your body, fella. Look at me and learn! I've got real fruit juice, soy milk, and whole wheat products, here. Psssh! The things some people put into their cart.
And watch out for those cookies on the floor.