Americans are very very good at code switching, which is why I think a lot of people think there are only one or two accents.

Is this why I can hear my Finnish friend's "generic euro" accent when no one else can?

(She travels a lot and has a very, very weak Finnish accent, but a fairly strong "generic European" accent. None of our other European friends can hear it; the only people who can are American and even then it's inconsistent).