Some have undoubtedly done this unwittingly, others more deliberately. And then there is the third category who have seen a good price and decided to not ask too many questions in case they don't like what they hear.
Alcohol is a key product for c-stores and the market is highly competitive. Prices in supermarkets have been rock-bottom for some time, and although I believe most independent retailers always want to stay legitimate, they can be forgiven for worrying about how they can compete. And it's not just the multiples that are the issue here if your next-door retail neighbour is buying iffy stock to keep his prices low, you need to think about how you compete with him, too.
But Customs are empowered to seize alcohol where they believe duty has been avoided, and charge you for the duty too. And they will do this even if you've got paperwork, and you think your supplier is legitimate.
It's another good reason to be ultra-cautious about your suppliers, but sadly there is not a lot of help available to determine exactly who is a legitimate supplier and who is not. The Federation of Wholesale Distributors proposed the idea of a registration scheme for wholesalers, but this was deemed unworkable.
So you can add HMRC to the list of organisations that are out to get you. And the answer to the opening question is yes, duty fraud is a very real problem for retailers.
Rio Ferdinand might not agree, but everyone else has a chance to get some action in the forthcoming World Cup.
C-stores are generally doing well, local shopping is more popular than at any time since the supermarkets started to expand out of town, people are more inclined to entertain at home than go to the pub these days, and the country is ready to let its collective hair down and enjoy life for the first time in about two years.
With so many positives, all that's left to do is hope for a sustained run from the England team. An early exit might be costly in terms of stock (one retailer I know has 2,000 England flags to get rid of), but also in terms of the fragile national mood. A good showing, a semi-final or better, could deliver the explosion in confidence and optimism that the business community has been waiting for.