We just got back from a trip a few days ago and while waiting for an embroidery to be completed we were chatting with a few CM's about pin trading one suggested to get them on Ebay. The second CM trading with my son said basically the same thing.."oh yeah she's right , that is the best place to get them. You can get them super cheap" close to exact words spoken.
This would lead me to believe Disney is not providing enough information to the CM's about real/fake pins.
Our local disney store had a huge amount of pins on clearance for 1.00 a piece. Some of the pins were actually 2 on one card (Phineas and Ferb). I bought all they had left. (About 50) We took these to trade this trip and I can tell you that all of the ones my Son traded for seemed to be fakes from looking on the sites that show how to find fakes.
Not that he cared , he had a blast either way and got the pins he wanted. So we didn't mind. But if you pay normal price for pins for your child to trade at the parks you may not be happy about ending up with sappers / fakes. Unless you spend a large amount of time inspecting each pin before you let your child take it you are most likely going to end up with fakes. I would venture to say most parents would not want to inspect each pin and then say no Son/Daughter you can not trade for that pin you want on the cm lanyard it may be fake!