https://www.marketwatch.com/story/this-is-exactly-how-often-...
So it’s likely anyone could have cash with traces of narcotics on it and tip off a dog.
Didn’t they also find that a majority of the drug dogs get signals from handlers to act like they found something? Seems like they find stashes of cash and use the trace amounts of drugs on money or the “trick the dog into signaling” technique to cash in.