My experience has been the opposite, and I think with the same CM on separate trips, months apart. (Deja vu experience.

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The CM was in uniform, wanted to do a personal trade, and made sure I knew it was a personal trade.
It took a short wait, but he went back stage and came out with LE's to trade for rack DS pins! So I did a 2:1 and we were both happy.

The DS pins really do go over big at WDW, from my experience. (Lucky for me.

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I have met the nicest CM's and made some of my best trades when I am not looking for a chest full of pins. I figure it must be fate.

But I hate to think CM's do as described above, as I think acts like that only give pin trading a bad rap and could add more (unfollowed) rules, policies and procedures for all.
Hopefully someone will report it, Disney will investigate, and put a stop to it.