>>”Only one question is needed: “Are you a Moslem?” and should be coupled with some investigation if the answer is negative and the applicant speaks Arabic or Urdu or Farsi.”<<
Add to that list: Pashto, Dari, Bahasa, Russian (or chechen, Nakh, Vainakh), Bahasa Melayu, Turkish, and French, German, etc. (since second generation western-muslim jihadists often aren’t fluent in other languages).
As for Turks, look for a solid middle class background. There is a middle class and they are educated and honorable westernized people. They assimilate when they emigrate. The other classes are highly suspect. The Turkish middle class is laying low. They get in their digs when they can. There have been riots and protests but they are pretty harshly dealt with by the aspiring Caliphate.