I've had it told to me by several people that migrated during the crisis, and have read several articles on it on Greek media.
Here's an example from an older article on similar issue (but with a happy ending):
Elsa Athanasiou, owner of Athos, complained to authorities that she has started receiving letters and phone calls saying things like “Go back to your stinking country!” or “Pigs, go home!”
Similar to the things I've heard. But there's other stuff for other ethnicities too, the popular press headlines for people from Southern AND eastern europe, the anti-islam protests that saw thousands of people marching, frequent attacks on Jewish establishments, etc.
Here's another metric:
(...) according to a 2013 study by the Technical University of Berlin, in 14,000 hate-mail letters, emails and faxes sent over 10 years to the Israeli embassy in Berlin and the Central Council of Jews in Germany, Professor Monika Schwarz-Friesel found that 60% were written by educated, middle-class Germans, including professors, lawyers, priests and university and secondary school students. Most, too, were unafraid to give their names and addresses – something she felt few Germans would have done 20 or 30 years ago.
> In the frequent verbal attacks immigrants from Greece (for example) face in Germany, in shops and public spaces?
I've lived in Stralsund, Berlin and now Hannover, and i'm extremely surprised that such a thing would happen. Have you seen that personally?