Sadly, no. Trades with cast members are not guaranteed to be authentic. The cast members do not vet pins they receive from guests for authenticity. So if they get fake pins from guests, they often pass them on to other guests.
Limited edition pins (which you'll often see abbreviated as LE pins) are often worth more in trade value than open edition pins (abbreviated OE--meaning they are continually restocked by Disney). When you're first starting out as a trader, it's good to get some traders of varying edition sizes (3000, 1000, 500, 300, etc.). When people trade, they often try to match up edition sizes, for example, trading one LE1000 pin for another LE1000 pin. That helps both sides feel that they are getting a pin that is worth as much as the pin they are giving up. (It gets a bit more complicated than that, but that's a good place to start.)
