Never bothered with DF in my travels, apart from the paid holidays in Germany resulting in my late Mum developing a taste for Bacardi Gold.
However, one memorable observation at Harwich and a member of the Army who wasn't that astute when it came to packing a holdall.....the bottle shaped bulges sort of gave the game away....last seen with that "uh !" look as HM Customs were opening it for him.
Talking of which, Felixstowe's "not so brightest" decided we were importing a glider from Germany ( representing RAFG in the Inter Services annual liver destruction competition, with some gliding at times) and, despite all the relevant paperwork, one decided we were importing the glider/ duty to be paid etc. It had been a rough crossing from Zeebrugge so not in the best of temperaments....hence a few Mancunian sentiments were offered as to his intellect / family lineage and personality. These appeared to upset the sensitive soul and, yep, "slight operational delay" leaving F'stowe as the car was searched (sentiments still be kindly offered) and, amazingly, nothing was found !.
All I can say, is, a ASK18 and trailer can carry a lot of DF. ...bonehead didn't think to search the glider.