That is a question I have often asked myself over the decades. Russian words in English tend to fall into two categories:
i) specifically Russian/Soviet referents: tsar, rouble, Gulag, commissar, perestroika, glasnost, vodka, cosmonaut [Russian spaceman], sputnik [Russian satellite], samovar and so on
ii) terms with a negative connotation: Gulag, commissar, ukase, pogrom, [actually maybe this is not a separate category].
So what might there be that is neither Russian nor pejorative?
It seems hard to derive bistro from быстро on chronological grounds, whatever the sign above might say.

The sable is tenné, not sable
Sable, as well as being an animal that lives in Russia and Poland is a highfalutin term for black as used by Shakespeare among others. There are a lot more соболь in Russia than there are soból in Polish, but Poland is nearer. Intelligentsia with that kind of spelling looks Russian rather than Polish (inteligencja) and the concept itself is just foreign rather than specifically Russian.
I quite like the word bolshie as a candidate here. While it is clearly derived from Bolshevik (so Russian rather than Polish) it has no trace of Russianness attached to it and indeed has a semi-affectionate diminutive quality. While the meaning of ‘difficult, recalcitrant, uncooperative’ may not seem especially positive, to the English mind these are not necessarily bad qualities–it may be different elsewhere, of course…