One way application developers publicize their products is by requesting reputed website to write an honest review of their product. For most of Mac apps I go with MacWorld, MacApp storm and then few forums. Introduction of Mac App store changes this game a bit, as user can write their review which can either crush the app to bottom or make is #1. Still Google results does matter. So blogs do matter to determine what shows up at top of result.
Last week was looking for an application to clean up Genre/Artist/Album mess I have in my library. And one app showed up o top Tidy songs. App was reviewed by maskable , makeuseof and few more reputed sites. But what showed up as first result for generic search 'iTunes Genre cleanup' was this website. If you look at the sites achieve you'll find all of their posts is about one thing 'TidySongs'. All this to make sure TidySongs comes as first Google result.
If the app is worth the money is different issue. But how will you trust such a company or developer indulging in such a shady activity?