right, I think it is for and against you, isn`t it?!
When I did language courses in the USA native speakers sometimes took me for English because of the language. maybe pronunciation. I think they flattered me. You are quite right to say that perfect mastering any foreign language supposes thinking in it. But we for whom English is foreign simply can't do it if (I repeat it, sorry) we don't live in this language environment. Speaking even good fluent English we stay Russians and I am not against. I'm proud of my country and treat people from other countries with respect. That's why I adore travelling abroad but then coming back home.