SevenCubed and lucy24 - many thanks for the comments!
If I understand this correctly, after reading various related threads (some a second time), it is a Google thing about which I can't do anything.
Since with fitting search terms the site in question comes up nicely in Duck, Bing, and Yahoo (not only that, but much better: those scraper sites don't show up at all there), I'll leave Google to its own game.
Metatags like "description" and "keywords" are therefore also out of the window for good now - had been hanging on them just for Google's sake, basically, and all they apparently do is make life easier for scrapers who get featured on Google. ;-)
PS: what does "organic" mean in this context?