@black: Is it that the mods cannot delete any feedback from the user's account? I have seen mods of other forums able to do that and hence I asked.
@green: OK just got the logic now and I added the users who send me feedback in my trusted list. I guess they have sent me neutral trust and hence the trust is shown as 0.
You did it the wrong way. Trust lists are not a way to say thank you for your green feedback to me; they're to include members whose judgments on others you trust since you value their opinion about other users.