I do not have enough experience with the trust system here but it is not good to allow members with negative trust (especially those with 2 or above) to participate in these campaigns. I understand the one negative trust might be possible due to some misunderstanding or revenge being taken but if someone has multiple negative trusts, the profile is suspicious. Only a campaign manager can tell the exact reason for such members being allowed to participate. One reason I can think of is that they are not getting enough participants with neutral trust because of multiple campaigns running.