I announce the student volunteers to the entire class at our next meeting, suggesting that complaints can be safely channeled through them. QC members often take the initiative to sound out their class-mates before and after class. Several have even e-mailed all of their fellow students just before a QC meeting to take complete stock. When we meet, I provide the quality circle members with an excerpt of the course syllabus covering the past two weeks. Some topics are not well connected with the thrust of the course, I learn.
Some readings are too old and too boring.
What annoying tendencies, I also ask, are vexing the class. The constructive criticisms are the stuff of a learning curve that my numerical ratings and written comments had never before provided. The hardest step, but one I also strongly recommend, is to have the quality circle members report briefly to the entire class at the next course meeting. This requires that you stand at the front of the room while your mistakes are publicly described. Your strengths also come out in the QC discussion, but in my experience students are often reluctant to offer much overt praise in front of the entire class for fear of classmate censure.