German to English Art/Literary Poetry & Literature

Setting: sanatorium on mountain
Context: doctor thinking about blood-red extract drunk by woman in Magic Mountain and the accuracy of Thomas Mann's writing.

The doctor has been disappointed by the inability of the sanatorium's cooks to produce the same bright-red extract that the woman drank at Berghof.

S- wurde unruhig, seine Stimmung verdüsterte sich, aber dann war er es leid und sagte sich, dass das ungewöhnliche leuchtend-rote Getränk vom Autor des "Zauberbergs" als literarische Ausschmückung erfunden worden war. Dazu sind sie ja Schriftsteller, um gutgläubige ***Köpfe*** zu verdrehen, die sich um die lebendige Realität keine sonderlichen Gedanken machen. In der Realität gibt es keine Zauberberge...

Credulous brains??? Credulous readers???

In my opinion it is not possible to say "brains" or "heads" in English. There are perhaps cases where this is possible, but not here. What I would really like is something like "boneheads", but that is going too far. The thesaurus doesn't have much to offer, and my own brain has even less.

Ideal perhaps would be a single noun that means "credulous people", but I can't think of one.

FYI: The question is derived from a Russian novella that has already been translated into German. I have also posted it at the Russian-English website: http://www.proz.com/kudoz/1676160, but wanted to consult you as well. In this case the Russian use of "Köpfe" is identical to the German, but in my opinion, as I wrote, "Köpfe" cannot be rendered in English with a direct equivalent.

Any ideas would be greatly appreciated!