Speaking as a user, I do find that low number of downloads and reviews for an app strongly correlates with low quality and outright scams. The problem is that you have all those shops cranking out barely functioning apps for trivial things just to get into the listing and hopefully capture a few installs from users who don't have the time or the inclination to do proper vetting. And those apps are so pervasive that they drown out the genuinely useful and well-made new apps.