I bring this topic up a good bit. Since early 2014, I've probably noticed at least a dozen fake-cop episodes.
Der Western (a German newspaper from around Dortmund) put up an interesting story.
Woman is quietly sleeping when her doorbell rings at 3:20AM. She goes to the door. They are in civilian clothing but showing a fake police badge. What they say is....they've got a warrant for her arrest, and the only way to avoid such an arrest is to pay the fine NOW. The journalist didn't say the amount and I can only assume it's a minor amount like an hundred or two-hundred Euro.
You can imagine yourself getting up and answering the door. You haven't had your coffee yet. Cops with badges. Your thoughts would not be clear. Fear would be the instinctive reaction.
However, in this case....the woman stood there and began to assemble thoughts.....then gauged it as a scam. The two guys realized this, and ran off into the night. Other than a basic description of the two....nothing else.
I admit....it's remarkable that you'd do this at 3:20 AM and think that you'd get away with it. But we've reached a point with fake cops....that people question things now.