Apple recently issued a note to developers concerning third-party App marketing services. In the note they said that developers wanting to promote their app should “avoid using services that advertise or guarantee top placement in App Store charts.”
They add that even it the developer is not personally engaged in the ranking manipulation or user reviews, using services that boost these rankings can result in the developer losing their membership. Apple then offers some tips for marketing apps the right way.
Here is Apple’s note on the matter:
Adhering to Guidelines on Third-Party Marketing ServicesFeb 6, 2012
Once you build a great app, you want everyone to know about it. However, when you promote your app, you should avoid using services that advertise or guarantee top placement in App Store charts. Even if you are not personally engaged in manipulating App Store chart rankings or user reviews, employing services that do so on your behalf may result in the loss of your Apple Developer Program membership. Get helpful tips and resources on marketing your apps the right way from the App Store Resource Center.
You can read the note here.