If your service is enough professional and transparent then i don't think you need to care about reviews whether its in favor of you or not. Let your platform users give their reviews by their own where your honest service will cover all fake negative reviews. Just not only in gambling site but also in google playstore apps you will see that some idiots give fake and negative reviews but i don't think anyone gonna waste their time by reading their baseless comments on review section. I won't say that every negative review is baseless where some users negative reviews are important which actually give you the opportunity to identify the weaker point of your project. After being notified by their reviews you can easily make the list of things which you have to implement in the next update.