Rudi,
"Quöllfrisch" from Appenzell, as well as some local specialities like "Monstein" from Davos, "Baarer Goldmandli" from Zug, "Turbinenbräu" from Zurich and surely some other local one are brewed strictly to the German purity law.

You are right Heinelen does not use hops and malt only, but is brewed with cheap indian corn, therefore it can legally be classified as "unclean" drink. This applies to Amstel as well, which is simply Heineken 2nd choice. Both should not be classified as a beer anyhow

I am not sure about the other lager beers you mentionned. AFAIK as I know the Swiss Lagers ( "Schwyzer Einheitsbrühe" )are tasting the same and are all violating the purity law stipulations. However the "Spez" variations of the Swiss brands are comforming to the law and taste definitely better.