Recently this has been the case with me, I am not talking about Peerfly but it's another another network they shave me right after the leads are added to my Balance. I got really furious because, everyday I noticed a change in my balance but I was not sure what was wrong with my balance (Kept changing). Then I sent an email to the Affiliate Manager, and she explained this by saying these are the advertisers who do these stuff for bad leads.
The question is what if the leads are not bad ? Who's gonna judge the legitimacy of those leads, the advertisers? even if the leads were bad,they were not deliberately done by the publisher and as an advertiser you cant expect all leads to be 100% good or legitimate. It's part of the game. It's sad but true, that publishers seem to have very little control over this.