For me, it's usually not the cashiers, it's the customers in front of me. Who block my getting to the card swiper thingy as they take forever to get their purse organized, peruse the receipt forever, etc. This last time, I was pretty well done, the stuff was bagged and the stupid bitch customer was still standing there organizing her purse my card was out, no way to get around her and she was totally oblivious. If I have any organizing to do, I grab my stuff and cart and go off to the side to do it!