Due to me being born and growing up right next to the French border of West-Germany and having been taught Spanish and Latin as well as basic ancient Greek in high school I would consider myself well equipped with a vast vocabulary in both Germanic and Romanic/Neo Latin languages which may have given me a little advantage when learning English.
If you learn a language by reading it is easy to appear more eloquent and to make fewer mistakes in writing than your average native speaker who seldom puts a book in his hands. For instance you won't see many foreigners mistake you're and your or affect and effect simply because most of us didn't learn English aurally. But it takes years of language immersion until you can trick people into thinking that you are a native while having an actual conversation. Though luckily I met very few linguists yet who scrutinized my articulation enough or witnessed me slipping up to instantly uncover my deep dark secret. I wouldn't go so far though as to compare myself to Joseph Conrad...yet.