How can I deal with bad product reviews?

I would say your first option is to check out what people are saying in the Amazon seller central about it! They love to have discussions in the forums about this!

https://sellercentral.amazon.com/forums/thread.jspa?threadID=238959

Get the customer to revise or remove the review.  If you receive a negative review, from that moment you have 60 days to get it either modified or removed by the customer who posted it. If it within Amazon’s terms of service to reach out to the customer and figure out if there is anything you can do to get the negative review changed. The other option you have if that does not work is to reply to the negative review and provide a solution that anyone reading that review can see and feel confident that you are willing to work with anyone having a bad experience!