Can bad reviews actually be a good thing?

Yes, according to a study done by Adweek. Customers considerably prefer eCommerce sites with ratings and reviews over eCommerce sites without them, however this is only true if there is negative feedback among the reviews. 

Without negative reviews consumers begin to doubt their validity, as well as their overall trust in the company.  Negative reviews are also necessary for consumers during the purchasing process so that they can work through concerns they may have before purchasing. 

If they don’t find answers on your site they will find it somewhere else.  So make sure your site’s ratings and reviews are as credible as possible by minimizing the number of reviews that your site filters.