Right now there is an incentive to not defend with your best teams and troops. So that player likely doesn’t use those troops much, but knows they will offer good gold returns for invasions. Those invasions, losses, earn the player the retaliations.
The developers work quickly to knock out cheating. From time to time something will crop up, and they will knock it out. In my opinion, the knocking out of true cheaters is done quietly and efficiently.
We’ve had a few threads, like the Treasure Hunt Thread, where people swore some of the people had to cheat to attain their scores, but it was looked into, and they seem legitimate to the developers.