DALLAS (CBSDFW.COM) – It’s hard to imagine a business turning away cold hard cash, but some stores and shops in Dallas are establishing strict new standards for accepting currency after getting burned in recent days by counterfeit money.

Customers at Urban Market who pay with cash better be ready for the scanner, the sharpie and a lot of suspicion from owner Gerry Knaus.

“Some people get very uptight about it,” Knaus said.

Knauss has been losing money because customers have recently been knowingly or unknowingly passing off real looking but fake $20 bills like these.

“It’s very frustrating to go to the bank and do a deposit and find out that your profit maybe for the whole day is gone,” he said.

The store now uses a scanning device and cashiers check bills with a yellow marker that’s supposed to turn black if it’s fake.

But recently, clever counterfeiters have been adding yellow marker lines to fake bills so it appears they’ve already been checked.

That’s what happened last week at Opening Bell Coffee.

“It is very frustrating because not only is the $20 bill not any good, but they also maybe received $18 worth of product,” said owner Pascale Hall.

Hall and lot of other business owners who are victimized, often don’t realize they have fake bills until they make bank deposits.

“You know they put the money in the little machine that goes dit dit dit and one pops up in the air and the lady says, ‘this isn’t any good’ and I said, ‘what do you mean it isn’t good’?”

It means lost revenue to small businesses that count on every dollar to stay open.

The Secret Service insists it’s not seeing an increase in counterfeiting across DFW.

But don’t tell that the owners of businesses who are getting ripped off and say they are only a few more bad bills away from not accepting cash at all.