Personally I have been hunting for years now and had never accidentally participate on a bounty without pay because, before my participation I will do a background check about the said project and the team members involved before my move to participate. Sometimes you don't need to blame the Bounty Manager because he's just a manager with little power on what goes and come in the project.
Bounty manager should have an analyst against the project that will managed by him. Sometimes I saw several bounty manager who stop the promotion and paying the participant with their own money when the project was caught as scam project. If I'm not mistaken the bounty manager is yahoo and I forget the project that he managed. Which is mean the bounty have a right to pay participant who promote the project if the project end up with scam because it's their fault. To run bounty campaign is not about counting the participant, see bounty hunter work or give a fee when the bounty has been completed but more than they have to know/differentiate legit and scam projects and the fees given by the project team must be in accordance with the initial agreement.
A red flag for them, and ADAB price is dumped 50%, that mean we get few dollars for a year promoting this. 
