Is this a centralized or decentralized system? I am not allowed to give a negative tag to people who I don't trust? Who do I tag instead because of this spammer, the manager that enables this user to defraud the company that is funding the signature campaign?
Less decentralized, of course anyone is allowed to give a negative tag, just like what you do. But, if people think you're leaving an incorrect tag, other users are allowed to distrust you too. So, be wise with your action.
If you do not trust someone,
Go to your profile, and then click on trust >> Trust settings >> Put a ~ and their username. In this case, it would be ~Bitcoin Smith and update it. If you trust some, do the same process, but without a ~. That's how you do it.
It's a different context.
Putting someone on distrust is either the user include/exclude an user you don't agree or the user leave inappropriate tag.
Neutral feedback is enough, if he really don't trust the user, he can consider to ignore the account.
Of course I would not trust the author of this thread with anything. This part of the thread indicates that negative trust is appropriate, other parts of that thread and statements by other members here indicate the contrary. So which one is it? Is a person able to decide what constitutes trustworthiness themselves or do they have to obey a preset list of trustworthiness rules that are imposed by others? If I am not allowed to tag him, explain why and help also with the following question if possible.
To make it simple, trustworthiness in this case are mostly talking about money. When someone spread incorrect information, it has no relation with money, hence it doesn't deserve to get red tag.