In addition to that, it looks like you might be rendering in draft mode ... the aliasing on the neck and the lack of detail around the eyelashes are what lead me to suspect that. While it's not related to the black spots, you may want to check your render settings to increase the quality setting more toward "production" to get rid of the rough edges there. As far as postworking, it's usually not a good idea for promos ... it could erroneously give folks the impression that you are trying to cover up texture imperfections vs. rendering imperfections.