A quite big Döner Brand in Germany(Berlin Döner) has shops like this and they aren't even that bad. They aren't outstandingly god but also not bad. Its maybe a bit overpriced for 6€(at least in my city it costs 6€).
Not in Berlin. The Brand calls themselves Berlin Döner and they operate in other Citys too. I personally got better Döner for the same money(in my region).