Google play have a good system addressing that issue, like you know, you have few offered templates to tap as for your satisfaction of app. Followed by star vote, alongside star vote you have a choice to write brief description of why you gave star vote that you did. And as for down voters... philosophy behind their minds is... like: Oh let's make mess, let me make someone suffer, I am evil, I won't let this guy have a perfect score... or hey no down votes/dislikes I will be the first! or just hey I wanna hate and make drama, be someones topic... or in his thoughts... that's what I gathered... mostly down voters are unsatisfied teenagers from what I learned.. people who got so used to be behind screen protection...