The use of drug dogs in civil forfeiture cases really gives the game away. What happens to the money once it's seized? It depends on the jurisdiction, but best practices are to put the funds into a bank account. This means the drug tainted funds are almost immediately put back into circulation.
Instead of a meaningful examination of documents and thoughtful analysis at the scene, LEOs get a dog to sniff the cash, and then simply check the box that says DRUGS. There is no crime they can point to, just a generic claim that carrying cash is strange and a dog alert shows a connection to drugs.