You pose an interesting question regarding when it is appropriate to post a negative review on a session experience.

I've posted a number of reviews on MF and they have all been positive in tone. That's not say that every session I have had has been what I had hoped, but I don't want to negatively impact someone's livelihood because I caught them on a bad day. I certainly wouldn't want anyone to do that to me.

I would not hesitate to post a negative review if I felt that I was the victim of outright fraud. I think subs should share that kind of information whenever it is experienced. I would also not hesitate to post a negative review if I had a session with a Domme who was obviously under the influence of drugs/alcohol or if the Domme whose play was blatantly dangerous and unsafe.

Other than that, live and let live!