I have never articulated my thoughts on Dietrich, but a blog (which has subsequently disappointed me and thus won't be named) inspired me to make an honest attempt. You will see my comment if you click the link, and I will also post it here after the cut.
Despite your opinion of Destry Rides Again, you conclude your engrossing post with a publicity photo from that film. By reconfiguring herself as a down home girl, Dietrich made the most viable personal and career move possible for a German-born actress in a nation that would soon declare war on the Third Reich as well as detain and intern Germans and German-Americans. Nevertheless, Dietrich failed to shuck off her exotic, unearthly traits as Frenchy and other patriotic heroines. She could never pass as an American let alone a mere mortal, which is probably why her character was named "Frenchy." In fact, I'd contend that Dietrich played a goddess incarnate in her Destry Rides Again role, who died for the sins of Bottle Neck. Her subsequent roles in the 1940s became an anodyne prototype for rom-com hacktresses such as Jennifer Aniston, but Dietrich gradually returned to form as a harem queen in Kismet, a Gypsy in Golden Earrings, and--unsurprisingly--a German in A Foreign Affair, Witness for the Prosecution, and Judgment at Nuremburg. During her career's twilight, Dietrich recommitted to the androgyny and chiaroscuro of her early Hollywood career, crooning "Just a Gigolo" behind a black veil to David Bowie--one of the few men who pulled off gender-bending as successfully as a woman--and finally denying us her face altogether as the disembodied voice in Maximilian Schell's documentary Marlene. Ramble as I may, I can't deny that you perfectly described how Dietrich's Sternberg collaborations initially possessed me and continue to haunt me. Thank you for your post!