Survey: How to deal with a bad review? What is the cost of a bad review?

We are trying to narrow down what is there to do when someone leaves a bad review on the socials. Do you start all over? try to find out more about the person? start a witch hunt and fire the culprit?

And more importantly, what is the true cost of a bad review? can we put a number or guess?

Your participation is anonymous and very appreciated !

Thank you in advance