Pin trading at the parks?

[Figment1964]

I recently bought some pins through Mousepins Online.

Here is their link:
http://www.mousepinsonline.com/tp40/default.asp?ID=18157

I was pleased with the prices.

 

[willis37862]

What pins are not tradeable? I read that they need to be stamped with Disney on the back?! Is there anything else I need to know about which ones you can trade and which ones you can't. Thank you.