If they are lots and each pin is in a little ziplock bag then almost certainly fakes. If still on card backs, more likely to be real.
That said, I didn't know this originally and did buy my kid a random lot on ebay when he first started trading, and no one ever mentioned anything to me when he traded. I know some of the ones he's gotten in trades are fake. He doesn't care though. He's not collecting as an investment or anything. He just wants to put them all on his display board.
Now I am careful not to buy him fakes as I don't want to support that kind of business, and I don't want him adding to the already overwhelming number of fakes that are already at the WDW trading spots.