Who is the governing body in pin trading that determines if a pin is real or not? There is no proof that the pins that my daughter has are real or fake. Now, if you want to call it "fraud", that knife cuts both ways. If I trade a pin that you claim is "real" and I receive what you call a "fake" pin from a CM, then the entire WDW Corporation has just committed fraud to me.
If the WDW Corp. cannot guarantee the authenticity of pins they are trading and they cannot guarantee the pins I am trading are authentic, then who owns liability? It is WDW Corp. They are the ones that are making it a business transaction by implying that the trade is 100% authentic. That means they are responsible for insuring pins traded to them that they in turn offer to its guests are 100% authentic.
We can go on and on and on about what pins can be traded. The fact of the matter is the pins on eBay can be traded in the parks. If they want to stop it, then WDW Corp needs to stop it. They CAN do this very simply by sending eBay a cease and desist notification. This will force eBay to pull all sales of pins offline if it cannot be proven that they are real. This is a 15 minute work effort by one of their numerous coucelors.