If the Bounty Manager knew that the project is scam and still promoted it than they deserve a negative trust.
But if they didn't knew about that, they are no different from bounty participants as they get paid to advertise.
If bounty manager are to be given negative trust for working on a scam project, bounty participants too deserve one as they too promote for payment.
How come that the bounty participant deserve to have a negative trust by participating a scam project? In the first place, participant give their trust on the bounty managers, second, bounty managers must examine their project carefully by conducting a verification on the team members of that project before accepting it and lastly, bounty participant didn't get paid by promoting a scam project.