Correct. You don’t know, so…
You avoid these types of transactions. Stick to transactions through the AH, or other supported means.
The root of the problem is that despite not knowing where someone got their gold, you continued with an unsupported transaction. It went bad for you, and that’s the risk you take in doing these transactions.
Classic WoW is not an easy place to make gold, so when someone is willing to get rid of gold on those servers…that right there is a major red flag. Gold is easy to make in retail, so why would someone be willing to trade allegedly hard-earned gold in SoD for easy-to-make gold in Retail?
But it is, Numey. As has been communicated to you NUMEROUS times over the last few days, these types of transactions are full of illicit gold and shady people. You are not absolved of any responsibility, because you are willingly participating and, knowingly or unknowingly, helping to perpetuate the rule-breaking.