Well you'd be wrong. If you put my slav wife next to me (American of German/English descent) you'd see she has the distinct slavic features: Yellower skin tone, pointy chin, more almond shaped eyes. She, her family, her countrymen (CZ and SK) all a little more Asian than western European. And the Western Europeans DEFINITELY notice that.

My wife doesn't have to speak to be treated differently than me. People just look at me and see a European (even though I'm not) and at her and see a non-European (even though she is).