I am running COD offer on GDN and suspect that someone is spam my ads by using some kind of robot to make fake click and fake conversion to my campaign and change their ip address everytime to avoid google detection.
I just wonder if this is possible or not? Or if you had experience about this, please share it.
Thank you very much.
This happens all the time, usually it's on smaller case and google refunds parts of these bot clicks automatically. I would recommend the same as jeremie suggested, try to check whether these fraudulent clicks come from specific websites or it's a large scale problem.