Most if not nearly all of the eBAY lots are Scrapper/Counterfeit filled. When you see lots of pins that are selling for $1.15 or so you have a pretty good chance that they are not going to be real. When you add in the eBAY and PayPal fess these folks are sourcing pins for $0.75 or even less - want to guess how they get them (besides stealing of course).
I have bought from a seller that really TRIES to keep their lots clean but even with their best efforts some junk gets through - and they usually sell for $2.00 a pin (NOT on eBAY).
When @ WDW most lanyards had fakes on them - mostly due to people buying pins on eBAY that are fake and trading with CM's for 'real' pins.
What to do with fakes - look sadly it is the new nature of collecting - trade for what you like and don't over analyze the pins. I can send youlinks on real vs fake but the pins should represent a fond memory of a trip - you are not going to retire on reselling them.
Enjoy trading and collecting, ignore the counterfeits - especially since you, I and even Disney have no means of controlling the situation.