Have you never been in one? It’s never full of fat tattooed slobs wearing pyjamas / tracksuits, so in comparison to any of the other supermarkets it’s fantastic.
Haha, I must admit I do tend to categorise supermarkets more on the clientele than the store itself and there's a definite pecking order, round here at least:
Waitrose > Sainsbury's > Tesco > Morrisons > ASDA > ALDI > Lidl