The big problem you'll find is that even looking at pinpics.com, it can be difficult, if not impossible to distinguish the real thing from a second, or knock off. Sometimes it's obvious, like a limited edition of 1/3, 2/3, 3/3, but the particular pin design has the wrong number on it, or the colors are all wrong. Other times, it is very hard to tell, and the differences are very subtle like the shine of the enamel, or the weight of the pin.
I didn't know a whole lot about pins last year, and thought my kids might get into pin trading, so I purchased a quantity from a web store that was suggested here on the DIS. After receiving the pins, and doing a bit of research, I found at least a few that I could positively identify as fake. It really upset me for a while, but then I started reading here about it, and realized that if the fakes are so common, and so hard to distinguish from the real thing that CM's often wind up with them, then you just accept that it happens.
Anyone who is really serious about not dealing with fakes needs to keep receipts and pin cards, and require them with any trade. Anyone who is trading without requiring them is taking a chance on getting fake pins. In the end, the only real difference between the fakes and the real deal is whether Disney is making money on them or not. If that doesn't concern Disney enough to bring an end to the fakes, then I'm not going to worry about it. If my kids trade, and get fakes, who cares, as long as they like the pin that is all that matters.
When we actually got to the parks, the only one who carried any pins was DS4, and he had no interest in trading them, just wanted to wear the lanyard with a couple of the pins on it. None of the kids traded any of the pins that they had, though the did get a couple of new Disney pins while at the parks, to remember the trip by.