The result of the last meso exploit (RIP lMira)

The "tax evasion" technique could be technically classified as an exploit.

As for the arrows... you unfortunately can't exactly prove without a doubt that those large sums of money that were given in exchange of "worthless" items were given as payment for a very valuable item. There's no direct link in the transactions.
If, on the other hand, you conducted this trade with the exchange of collateral and then returning the collateral items to the owner for the mesos, you wouldn't have aroused suspicions.
Conducting such transactions with collateral is safer in terms of scam avoidance anyway.