As with many things, it depends on the merit of the review. If a single bad review is enough to seriously damage a business, there was probably already something wrong there, whether that's the product, service, reputation, or a lack of positive reviews to balance it out. Though I think most reasonable people don't expect a business to have a perfect record (there's always gonna be one person who wants to be the review that ruins a 5/5, for one). What they look for is whether complaints are isolated incidents or part of a pattern.
Personally, the most important thing to have is good service as a provider and a client. Though I suppose it depends on how ethical you are as a business. You could just have really excellent marketing, burn through your bridges just for fast cash, and ride that wave out until your service inevitably bites it.