ONE MORE THING

Oh I forgot most important lesson that I learned from watching pro shopping housewives scavenge for food. When someone's cart is barely blocking the aisle you should definitely NOT

-nudge it slightly to the side to go by
-say excuse me and get the owner of the cart to move it.
-go around it
-and browse the items in the vacinity

No the correct play is to park your cart right next to it, bulge your eyes out and cough as passive aggressively as you can.