Google deleted 60,000 "low-quality" apps from Play Store

Google deleted 60,000 "low-quality" apps from the Google Play application marketplace in February 2013, according to a report

The report indicates that a large number of apps in the MP3/ ringtone category were deleted as they might have been violating copyright, which is against Google's policies. Google doesn't disclose app removals publicly.

While Google doesn't pre-approve apps like Apple, but it does scan its app store for violation of terms and pulls them out if they're found to be guilty, as noted by the report. 

Google had also removed AdBlock Plus, an app that lets users block advertisements while browsing the web, in addition to other similar apps such as AdAway, from the Play Store, in March. 

 by TechCrunch. The online publication says that it learned of this round of app deletions from a company in the mobile app industry which tracks these developments without specifying the company's name. However, it does give a disclaimer that some app publishers might have pulled the apps themselves.