i personally think unnecessary 3d is worse, at least with bad cgi you can kind of laugh at it
http://www.youtube.com/watch?feature=player_embedded&v=yMwmqp3GLMc - a perfect example of terrible cgi or the terrible cgi groundhogs from the Indiana Jones kingdom of the crystal skulls

example of unnecessary 3d- titanic 3d.... the movie was bad enough in 2d