I've always wondered why M&S in Warsaw bothers stocking white sugar.
This is what I've never got. I used to go to the Polish Shop in Glasgow and I would buy mostly pre-prepared Polish food or Deli meats. But you would see people in there doing their full weekly shop in a little tiny Polish shop when there's a tesco across the road. I thought it was mental, but if you were new to the country and unsure of the language then that could be a reason to stick with there at the beginning.
I often go to Kuchnia Swiata to buy Irn Bru when it's in and sometimes Marshall's Cheesey Pasta. Both of these things are ridiculously unhealthy and full of chemicals, not to mention expensive, but it tastes like home so it's nice for a treat every now and again. I would never contemplate (or be able to afford) doing all of my shopping in such a place though.