What is the dirtiest currency?
I'm curious to know, what do you mean by the "dirtiest currency"? Are you referring to the cleanliness of physical bills or coins, or is there a deeper meaning to this question? Are you asking about the most unethical or controversial form of money, perhaps one that's been used to fund illegal activities or has a history of being tied to corrupt practices? Alternatively, are you referring to the currency with the highest transaction fees or the one that's most difficult to track and trace? Clarifying your question would help me provide a more accurate and informative answer.