Is it a bad idea to use our meta description as a short description of a product on that product page?

[USAMM]

Does this count as duplicating content even though the meta description has no effect on search results?

[SoleGraphics]

Its not a bad idea, but it might not be the best idea. By doing so you're limiting your product description to a short one, and if that's the only thing describing the product it might not be enough to attract the attention from the search engines. As for the technical answer, the meta description and short description won't count against each other.

[DennisSeymour]

A lot of companies actually do this but I would suggest doing it separately (with great page content) as it has given me the best results with all the ecom sites we've worked with, even without link building.

There's actually no duplicate issues there as I haven't seen one yet for that situation.