They must train at the same place as their passport "police." I was very tempted to set off an international incident when a passport official in Frankfurt screwed up his face into a terrible scowl when he saw my U.S. passport, then literally threw it back at me. He did the same with every American in line. The Germans hate us but not single one threw my money back at me when I did business with them.
Sorry you had that experience. But, no, that isn't the case. Germany has a specially trained federal riot unit. You can always see them in action in the news when there's a G8 summit in Germany. All other local riot units get training and assistance from them, and IIRC most polizei have to serve time in a riot unit.
The border patrol does the same with Germans, too. They´re unfriendly. If I were in charge, I´d order them to greet everyone with a smile and a “welcome to Germany”. They should behave as if they served the people, and not themselves.