How are people listing USD on the flea market?

[African_Plz]

I have noticed some listings on the flea market trading USD for barter items like wires or dog tags. It looks like you are getting say 400 USD for 1 dog tag (Great deal right?) but when you do the trade you only get 1 USD for the dog tag, basically getting scammed. Is this a bug or exploit? How is it done?

Before i get abused for "You cant list currency", here is a screenshot for both USD and EURO

This being said, there is only 1 page of listings for both currencies so id imagine not many people know about/how to do this

 

[keepa34]

Non-ruble currency works the same as any other item where you can put multiple of the same item up. 

The flea market just shows that there are 400 1 dollar stacks available to trade for each dogtag. 

[African_Plz]

1 hour ago, keepa34 said:

Non-ruble currency works the same as any other item where you can put multiple of the same item up. 

The flea market just shows that there are 400 1 dollar stacks available to trade for each dogtag. 

Ok, but how did they actually list the currency? It shouldnt let you