As a property manager, you're always at risk for negative reviews, especially from a disgruntled tenant. You may think these are unavoidable because of your obligation to represent the homeowner in the transaction, but there are good ways to avoid negative reviews, and respond to them if you do get them.
Communication is key. Sometimes your customer will not like the message, but avoiding the message will turn a mediocre experience into a bad one (that ends in a negative review). How many negative reviews are out there from applicants for a rental property they didn't get - just because they didn't get a call back or email to tell them they weren't approved. Always respond - even if you don't think the customer will like the message, a kind, friendly, response is less likely to end in a negative review.
Be flexible when you can. You may have a way a certain process goes in your company, but often we let that get in the way of finding a reasonable win-win solution.
Maintenance. On of the biggest drivers of negative reviews is the maintenance process. It's true there are many reviews related to the overall condition of the home, but so many are related to responsiveness (or lack thereof) from the property management company. Have a great process that makes you easy to reach on maintenance issues. Trying to do it yourself, between collecting rent and leasing properties is not a great strategy.
Finally, if you get a negative review, reach out to the reviewer to see if you can resolve the issue and get a new rating from them. Either way, put a very nice comment on their review. Remember - you are not responding to the reviewer online - you are responding to the reader of the review. A vindictive or explanatory comment will only make you look bad to prospective customers (you are not going to convince them in a brief paragraph that the reviewer was wrong). Just write something nice about how you are sorry it didn't work out better for them, and to call you personally if there's anything you can do to assist.