Forum ratings are widely misunderstood and frequently misused. In a support forum, for example, ratings should only be applied to support given, and should rate the quality of the support (Martin D in http://moodle.org/mod/forum/discuss.php?d=89722)

We need a Help button next to the Ratings dropdown that explains the ratings game. If possible, it should have the rubric for ratings specific to the forum. The help file should be either completely generic (is it possible?), but ideally it should be specific to the scale used in the forum.

See this discussion: