Are there some users exempted from the consequences of the red trust? Or first what are the consequences of having a red trust?
It entirely depends on how people see the negative feedback on your profile. Some negative feedback is genuine and even has proof in the reference showing that you can not be trusted, while other feedbacks are just sent due to disagreement between members (Not a correct way of using the trust ratings)
For example, I could send you negative feedback saying "You are very annoying" yet you never scammed anybody. So some people can still trust you and do business with you.
2. Amidst this, people are still patronizing the company. Does it therefore mean that the red flag or trust is not the true representation of a user. Can a user be a saint and yet red trusted by many?
The people patronizing the company also have red trust for different reasons. Why should you trust what a bunch of untrusted thugs tell you?
I mean, they are all coordinating to defraud more people.
3. These campaigns pay good money. Where exactly does this money come from? From the defrauded individuals or the company generated profits?
From fraud. If they had genuine intentions or were making lots of profits, they would have sorted out all the issues at hand, just like the other company around the forum.
4. Even if the forum cannot or does not want to do anything about scam moderation due to certain reasons, is there no a specific amount of red trust a user should get without a corresponding positive trust and get banned?
The moderation policy is so clear on scams. Scammers don't get banned. It's entirely up to the community to label them
5. A user who in past associated with scam and on the long run sincerely repents, is there a way the red trusts can be reversed, or is it as irreversible as the merit?
I depends on how forgiving the member who left the feedback is. But Admin or Mods never interfere with the feedback or dispute.