Although there are different levels of technological sophistication in producing fake bills, more often than not it is possible to identify them. Here are a few techniques you can use:

The $3 bill has been released more as a practical joke to poke fun at celebrities like Bill and Hillary Clinton, Michael Jackson, and Richard Nixon. There is a saying that goes with this, "Queer as a three
dollar bill."

There was a $22 bill made by Lawrence Wagner who was a U.S. Presidential Candidate. He printed the bill because being a numerologist he believed that the number 22 was very important. The Federal Government indicted
him for the crime of counterfeiting, but he was let go because technically you
can not counterfeit something that doesn't exist. - undetectable banknotes

In 2001 and 2003 there were two occasions where a $200 bill was used to pay for items. The one bill had a picture of President George W. Bush on the front of it.

One of the most common examples of bill consolidation fraud is a debt consolidation company that pretends to be nonprofit. Such companies promise to clear a borrower's debts for a nominal charge and then later charge
a sizable fee. It is, therefore, advisable not to sign any contract with such
firms. Sometimes, a borrower's equity is stolen through bill consolidation
fraud. In this case, a lender or a mortgage agent contacts the borrower and
promises to combine all his debts into a single repayable loan. Later, in order
to yield huge profits, he compels the person to borrow further. This may
sometimes pave the way for a loss of property on the part of the borrower. - fake bills to print

Another example of bill consolidation fraud is a firm that promises free debt consolidation that is not actually free. Bill consolidation fraud also appears through a plethora of media sources. Other methods of bill
consolidation fraud include phone solicitations, print fraud, and online fraud.
In the case of phone solicitations, scammers contact borrowers and ask for
account-related and personal information. Print fraud utilizes local newspapers
and magazines to publish fake advertisements, coming up with special rates and
offers for bill consolidation. Online fraud occurs in the form of fraudulent
e-mail. Sometimes, scammers use logos and images of legitimate companies to get
information about the borrower's account.