That's interesting, because the customers at Aldi here in Germany are basically a cross-section of the population, but tend to be middle/higher middle class. Especially after the update to most of their shops during the last 7-8 years [0], most Aldis look really nice inside. This combined with the huge advantage that shopping at Aldi is really efficient (the stores are not large, for most items, you have only a single option to select from which usually has an excellent quality, and the cashiers are arguably the fastest in the industry) makes Aldi very attractive for people who could easily afford shopping at a non-discounter. Sure, I enjoy the occasional hour-long visit to a large supermarket with the family on a weekend, but after work? I want my shopping done in 10 minutes max without selecting from 30 brands of pasta and go home.

At least in larger cities, the average Lidl often looks a bit run-down and grimy, and the customers tend to be lower class (that's not the case in rural areas, however). I always found that interesting, because prices / quality are basically equivalent (although I tend to prefer Aldi products). I live near the border to France, and the situation there appears to be similar.

At least a few years ago, however, Aldis in Switzerland also looked very run-down (though not as run-down as Denner) with distinctly lower-class customers and a much larger focus on selling alcohol than in Germany.

[0] https://www.augsburger-allgemeine.de/wirtschaft/Bilderstreck...