Patrick Palace has some good ideas in his ABA Solo magazine article How to Use Bad Reviews to Attract Good Clients (ABA members only). The most important idea is that negative reviews can be a net positive–if you know how to respond. Here’s one specific tip:

Timely responses are even more important for negative reviews. Don’t let a negative review sit without a response. Readers may adopt it if you don’t respond. Your response should be targeted to the readers of the review. Don’t make the mistake of thinking that you are responding for the sole purpose of answering the reviewer’s challenges. Your response should take the higher ground and give value to all readers. Never suggest that the reviewer is unreasonable or wrong. In fact, give the reviewer full deference and grace. Thank the reviewer for bringing these issues to your attention. Taking the higher ground is always the best method. For example, by answering in a positive manner, you aren’t seen as aggressive, defensive, and angry. By inviting the reviewer to contact you personally to discuss the problems and look for a solution, you show your reasonableness and willingness to hear your client’s problems. Your response tells readers that you are ready and willing to fix their problems. You convey that your clients/customers are not just numbers, that profit is not your only goal, and that customer service is your priority. By answering quickly, you tell everyone that you are responsive and that reviews are important to you. In the end, remember to be empathetic. Be real. Use the review as an opportunity to gain other readers’ trust.