While searching my notes I found....
A long time ago (1970's) in Stuttgart, Germany I was a Staff Sergeant working with the U.S. Army 42nd Military Police Customs unit.
While working with the 42nd Military Police Customs, I ran across just about every type of customs scam you can think of. Our unit had Customs Inspectors and Customs Investigators. I was one of the Customs Investigators.
I did great things like checking ID cards and ration cards at the military facilities. I also investigated the illegal use of those ration cards and ID cards and the giving and selling of US goods to local Nationals for profit.
Yes, U.S. Soldiers paid their rent with booze and cigarettes. Go figure. Of course as it turned out US soldiers had been dealing on the black market in Germany since World War II.
I was assigned to accompany two German Customs Agents for days at a time while they followed up on complaints by jealous German neighbors about Germans who were receiving US goods without paying the German tax on them.
We would drive out into the German countryside near Stuttgart, Germany and check on these allegations. This was interesting since I did not speak that much German and the Germans did not speak that much English.
We would walk up to the door, the German Customs Police would show a German Customs madallion and we would be invited in. Once inside the Customs investigators would explain the allegation and then look through the house for US items.
Once they found US items they would asked me to verify the items were in fact US merchandise. Then the German would have to produce a sales receipt to prove they had paid the German tax on the item.
In most cases, the German had no receipt and would tell the Customs investigators they were receiving gifts or payment for rent from US soldiers.
The German could then pay the tax and they would have no problems from the German government. On the other hand, the German would then give me the names of the US soldiers who would be investigated for US Customs violations.
The soldiers would be arrested and in most cases, reduced in rank, and pay a fine, and even be discharged from the service. Not a very fair way of dealing with the situation, but that was the law.