There are dealers and exchanges who abide by regulation in one or more countries, and some that don't. It's also public record where transactions travel on the

There are dealers and exchanges who abide by regulation in one or more countries, and some that don't. It's also public record where transactions travel on the blockchain, so if it was ever noted what address the funds entered, I imagine it could prove difficult to dilute the transactions enough that the ledger wouldn't be accepted as proof. But I'm just speculating on that last bit.