I Am The Middle

Greenwald is talking specifically in this post about Marty Peretz's assistant, Jamie Kirchick, but it's still a valuable, concise description of a common technique to watch for:

As we've seen many times and in many contexts, one of the most empty-headed, trite and deceitful pundit techniques is to take one's own viewpoint and, without an iota of polling data or other empirical support, attribute it to the "average/ordinary/moderate American" and then, with deep concern, warn political leaders that they will harm themselves politically -- will alienate the fair-minded moderate voters -- if they don't follow that view.