Won't name which one, but one of the leading ones, a superstore.
I used the toilet there and it was absolutely disgusting. The floors covered in soggy paper, not one toilet that didn't have urine or worse splashed all over it.
Used one as I was desperate.
Reported it in a polite manner and the customer service lady was understanding and said she'd pass it on.
Ate in their café as was pretty hungry and they had a 50% deal on. You really do get what you pay for I guess, but that's on me really.
Anyway that was just as bad, only about 3 customers but the floor looked like it hadn't been swept in days, staff stood around, dirty tables. Saw one kid wipe a snotty hand on the table, though I suppose that's not exactly the supermarket's fault.
I ordered a burger, wasn't expecting fine dining but I was served one of those toasted muffins with an evidently frozen burger, could tell by the taste, and those microwave chips.
It's my own fault, can't expect haute cuisine for only a few pounds I guess.
Shame how standards are so low though.