My understanding is that the venting dylan604 is describing relate to airflow around the firebox / chimney, rather than in or out of the firebox.
An incorrectly-placed firebox intake, or even a poorly-drafting open-hearth fireplace, can indeed dump smoke (and carbon monoxide) into the living / heated space.
An incorrectly-placed firebox intake, or even a poorly-drafting open-hearth fireplace, can indeed dump smoke (and carbon monoxide) into the living / heated space.