This article is from the PEZ candy and PEZ dispensers FAQ, by sharpe@dg-rtp.dg.com (Chris Sharpe) with numerous contributions by others.
This answer is the same as from any collector. Whether you open them
or not is completely up to you. If you want to retain the highest
resale value, then don't open them (but also keep them locked away in
a humidity controlled environment away from UV radiation...). If you
collect them just for fun then it's up to you. I like the cards, so I
keep them unopened. It's difficult to display them in the bag, so I
open them. Only keep them in the bag if you're going to resale them.
There are a few exceptions (older dispensers like the Stand By Me
special that *must* be in the bag). The cards are favored over the
bags, but I'm not sure they're really worth more (except that you get
one more pack of candy).
 
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