I had exactly the same experience the handful of times I've used AdWords.
I also just released my app on the Play Store a couple of weeks ago, and had exactly the same thing within the first 48 hours - a bunch of suspiciously similar Gmail accounts, none of which had actually used the app (I know this because no backing accounts were made in the database).
The only conclusion I can make is that there's huge amounts of fraud, but the average advertiser either doesn't know about it, or their advertising ROI is high enough that they can simply eat fraudulent clicks as the cost of doing business.
I've said it before, though - gut feeling is that internet advertising is long overdue for a reckoning.
I also just released my app on the Play Store a couple of weeks ago, and had exactly the same thing within the first 48 hours - a bunch of suspiciously similar Gmail accounts, none of which had actually used the app (I know this because no backing accounts were made in the database).
The only conclusion I can make is that there's huge amounts of fraud, but the average advertiser either doesn't know about it, or their advertising ROI is high enough that they can simply eat fraudulent clicks as the cost of doing business.
I've said it before, though - gut feeling is that internet advertising is long overdue for a reckoning.