Odds are in you traded for pins from a CM lanyard, you got scrappers. Some are good and hard to tell they are fakes, others are pretty bad and can be easily spotted right off the bat. You can check out pinpics.com and their pin forum to see pics of some known fakes, and reasons why they are fakes.
Things to look for -
* Unclean edges. Places where there are bits of metal flashing left on the edges where if overflowed the mold that would normally be trimmed up, or areas between pieces of the pin that stick out that should be clear of metal, but instead have metal between them. (IE look at the Vinylmation pins, many still have metal between the arm and the body)
* Off colors. Often the colors aren't what they should be. I have seen some Belles whose dress has been a radioactive green yellow instead of the normal yellow color.
* Off paint. Real pins can make it through QC with spots left blank, colors in the wrong spots, and things like really bad pupils in the eyes, but scrappers are much more likely to have these things.
* Bad back stamp. Falls into two types. Some pins (like most of the Vinylmation pins) have a pattern of Mickey heads on them. Scrappers often have the heads running from left to right instead of top to bottom (if you look at it upright, half the heads should look correct, the other half upside down. If they are sideways its a fake). Others won't have the heads go all the way to the edge of the pin. So the Mickey head would just end 1/16" of a inch before the pin does, which is a dead giveaway its a scrapper. The second type would be where they used the wrong back stamp. The odds of you knowing this while trading in park are slim to rare. But the Official Disney Pin Trading logo has the year in it, sometimes they stamp them with the wrong year, or use the Mickey head pattern when they shouldn't have, or use a DLP stamp when it should have been a WDW stamp, stuff like that. And unless you are hardcore knowledgeable about the pin in question, is very hard to spot. Especially since Disney does make changes to the backs, as well as sells the same pin in multiple years.
* Weight. Scrappers are often made with a cheaper lighter type of metal. So a scrapper would feel lighter than the corresponding real pin. After a while you can get pretty good by telling by feel if it seems light.
Basically it comes down to the pin just not feeling right. If something about it feels off, odds are its a scrapper. Some of the most commonly scrapped pins are the CM Lanyard pins, as those tend to be a little smaller, and have simpler designs. So a huge chunk of the pins you see with a silver "hidden mickey" on the front are probably scrappers. Disney doesn't seem to care too much about it, and some are so good that even their pin designers can't tell they are fakes. There have been times where people have brought pins to the pin trading nights, and asked the designers if it was fake. And the only way they can tell its fake, is when they pull out the official book of pins they produced, and they see that it's not in there. Some are completely new sets/series based off of other things, others are just some that were never made. For instance the Vinyl sets don't always include every pin, so some scrappers make pins of the ones that Disney didn't.
As with any collectible, what it comes down to, is are you happy with the pins you bought/traded for? Odds are you won't ever get back the dollar value by selling the pins down the road unless they are really rare/exclusive ones. So by making trades for pins that you feel are a good value, and by getting pins that you are happy with, then you have come out ahead, and had a good time doing so.
