Funny, I was chatting with a German friend last night, who works in a hotel bar, and he bemoaned the number of guests who thought he was Dutch.gertmenkel said:NO, I'm not German, but Dutch (yes, there's a difference).
Having known plenty of both, I don't think I've ever had trouble differentiating the accents.
Localising an accent to a particlar part of Holland or Germany (or almost any country, for that matter), now that's hard.