I have placed my app on several alternative Android app stores. The Android Market accounts for 60-90% of my total downloads on any given day. That was until I noticed that my novelty game, Finger Arena, had been pirated on several Chinese APK sites.
On one (520apk.com) I found:
About two months after Finger Arena came out, I reached 5,000 downloads on the Android Market. I can see from the Andoid Developer Console that most people who use it are either from Taiwan or Hong Kong.
So only ~5000 out of more than 46,000 downloads are from the Android Market! At least 90% of my user base is using a pirated version.
I took apart the APK and had a look. It was mostly intact, although my certificate denoting me as publisher had been stripped off.
So now I know why I had been getting a huge increase in the number of ad requests using AdMob (that AdMob didn’t fill, presumably because the IPs are from within China and they have no market for advertisers there). This has drastically reduced my eCPM to almost nothing. I’ve decided that putting house ads at 100% is probably the best option for the time being.
(I also have doubts about the reliability of statistics on 520apk, of course. I’d actually prefer that they aren’t real and that people like to play my game over and over and over again.)