It scared me for a minute when there was press going around regarding Android apps sending push notifications which double as ads. Of course, Google happens to have updated the Play Store terms to combat this issue... and indeed, it actually is working. Then again, Android isn't the only OS with the problem:
That's right. This was taken on an iPhone 4S running iOS 7 here, and as you can see, there are horrible reviews of an app describing similar issues. Ads that double as notifications, ringing the phone's bell. Only this time, they're visible not only in the notification center but also (!) on the lock screen, such that merely unlocking the device is the same as clicking on an ad.
I'm sorry, but this is extremely bad app development practice. One reason why users submit so many one-star reviews to some developers is because of nasty tactics like this that essentially force the user to want to click on ads. It's basically adware as an app, and it makes users feel completely intruded upon.
Now, sure, there's the moneymaking argument. Uh, that's what in-app purchases and non-intrusive ad banners within the app itself are for. Alerts? Yeah, I've seen alert ads too, and we all know how intrusive they also can be. Well, at least alert ads also only open while the app is open. Not so for push ads, which makes them purely a greedy, controlling, abusive means to stifle users and have that reputation backfire.