Dallas (CNN) -- Counterfeiters -- agnostic toward NFL teams, antagonistic towards trademark laws -- are flooding the U.S. with fake NFL jerseys.
And in doing so they have helped create another Super Bowl tradition -- the flea market bust.
Federal agents in recent weeks have scoured T-shirt shops and Craigslist postings looking for bargain-priced NFL merchandise -- a tipoff that sports merchandise may be bogus. And they've followed up with raids, hauling away a trove of jerseys.
So far this year, Immigration and Customs Enforcement (ICE) and other agencies participating in "Operation Interception" have confiscated 36,273 counterfeit trademarked items nationwide, with more expected through the weekend. The value of the haul thus far: more than $3.56 million.
In some cases, it takes a keen eye to discern a fake jersey. But in other cases, no Sherlock Holmes powers are necessary.
Some jerseys have the names stitched upside down.
"That would be a clue," deadpanned John McNair, an ICE supervisory special agent in Dallas.
More typical clues, McNair said, are shoddy craftsmanship, mismatched lettering and serial numbers that are repeated instead of sequential.
Fakers try to dupe customers -- and the government -- by replicating the NFL's main security feature -- a hologram tag attached to each garment. True holograms reveal distinct pictures, but the hologram on counterfeit goods "really is nothing more than a shiny sticker," McNair said.
"We've got (counterfeit) hats, shirts, telephone cases, it runs the gamut," said John Chakwin, head of ICE's Dallas office and the federal coordinator for Super Bowl security.
Chakwin said much of the contraband is manufactured in China and smuggled into the country in containers with fraudulent paperwork. Shirts, for instance, could be listed as bedsheets.
The sale of counterfeit goods results in lost duties and federal and local taxes, Chakwin said.
The fake sporting goods market also contributes to people who counterfeit other products, including fake pharmaceuticals, and batteries and other goods that have not been tested and could be dangerous.
"Some of these stories that we've hit sell nothing but counterfeit products," he said.
The International Anti-Counterfeiting Coalition estimates that counterfeiting costs U.S. businesses $200 billion to $250 billion each year and is accountable for the loss of more than 750,000 American jobs.