Shrinkwrapping is not a dumb question.
Many stores like Electronics Botique and Babbages open new games, and
either sell them open, or re-wrap them.
Ebay and their counterpart Half.Com are just sources for people to sell
games. Depending on how honest someone is (read their
reviews/ratings/etc) and find out.
Not all new games have plastic hang tabs on the back. Also, a retailer
can attach plastic hang tabs if needed.
There have been items I have needed to re-wrap because customers have
removed or partially removed the shrinkwrap.
An honest seller would tell you if its factory wrapped, or a rewrap.
Brian Satinover