That's a good question, Atla.
I think it depends on the instructor, and even if it's not the instructor themselves I'm sure they have fans looking for what people have posted about their workouts. Background exercisers who may have been in a workout, for example might report back to the instructor.
Jessica Smith's new Lift and Shift program comes to my mind immediately. Even though most of my reviews have been positive, I do have some negatives that I tried to post the other day.....and VF timed me out, so I couldn't comment in the "Refund Lift and Shift" thread.
It's only fair to post negative as well as positive thoughts, opinions and reviews.