Not only are developers who sometimes scam or cheat but currently there are so many participants who cheat by using other people's profile links, maybe to reduce cheating, bounty managers must use Proof of Follow by using screenshots and to overcome scam projects there should be a special community which takes care of the developer data verification to avoid a scam
While doing signature campaigns, the users can't rely on fake profiles. So the vast majority of the cheating cases can be found with social media bounties. Taking a few basic precautions can eliminate 99% of the cheating as far as social media bounty is concerned. But the big question is whether the bounty campaign managers want to put the extra effort to flag these fake profiles or not. In most of the cases, the campaign managers are only interested in their salaries and they are not much concerned whether anyone is doing cheating or not. I have seen cases where the campaign manager refused to disqualify the participants, even after adequate proof was presented to show that they were cheating.