The majority of ratings seem to be warning people about red flags, not punishing provable scams. IMO this isn't a bad thing, since once someone has scammed, it's kind of too late.
What do you think about splitting the scam rating, with a "warning" rating for scammed previously OR you strongly believe that they will scam in the future, and a "scammer" rating for scammed previously AND you strongly believe that they will scam in the future? And then if you only have warning ratings, the indication displayed next to posts will be softer.
I think that you and I have a fundamental disagreement on this stuff, though:
Predictability and guidelines are often good. I wrote some Trust guidelines recently, and I may write more. But I don't believe in having a set of hard rules which is to be applied to all cases. Whenever an argument starts looking like it was written by a lawyer, or relying overmuch on precedent, you've stopped thinking about the real case and have started using rules to retreat into moral and intellectual laziness, divorcing yourself from the decision you're about to make. If you're making a decision about a case, then you're responsible for that case, and you can't say, "I don't agree with it, but I was just enforcing the rules." Every case needs to be handled individually.
I think you already set the system up to do that by creating neutral ratings. I don't think the trust system needs more additions, what it has needs to be more tightly directed. The more parts you add to a system the easier it is exploited or broken. I realize you don't like hard and fast rules, and I understand your fears here, but you should also realize if those are actually your primary concerns, the current environment allows for MORE of that type of behavior not less of it.
The fact is a negative rating is a penalty for people and inhibits their ability to trade here. These warning ratings will do little but slow down fraud at best. Either they should be a warning which can be widely applied, or a penalty, not both. If it is both then the counterproductive element of catching too many people in the wide net is a problem. This is why I am advocating for using neutral ratings with scam accusation/reputation threads referenced as the warning. This benefit is two fold, it reduces the signal noise of false ratings, and it teaches users to actually read the ratings before trading. Then when you see a red tag it actually means something.
You may want to run this place in a more anarcho-capitalist friendly way, but as I said before the forum is still inherently centralized, there is no way around this. As a result you inherently are the one to define these rules. When it was smaller this free for all kind of approach worked better, mostly because the community was more cohesive.
Now it is getting larger and in some ways unmanageable in the same ways, and frankly this obsession with not wanting any hard rules is hurting this community, not helping it at this stage. I don't think setting up a standard of evidence of theft, violation of contractual agreement, or violation of applicable laws for leaving a negative rating is at all excessive, and in fact is quite minimalist. Furthermore as I defined it would actually allow people to have a fair overview, not just a summary execution by suspicion and its over with.
Currently most of the people in control of the trust system have no accountability as it is. The arbitrary nature of the "guidelines" creates so much ambiguity you could drive a bus through to avoid responsibility for a bad rating. The standard I am advocating for would absolutely leave people responsible for their own ratings. Not only would most people expect them to back the rating up with evidence, but it would have to make sense in an objective way, as opposed to the non-standard we have now of "I feel like...[insert crime here]".
You are afraid of this place morphing into the standard authoritarian type environment. I get it. What I don't think you do get is that we are already largely there, it is just some thing you never see because of the complete ambiguity and lack of accountability of the people doing the ratings and exclusions. Anyone who has a complaint is easily dismissed as a scammer without a second thought, and to you it is as if it never even happened because it happens so often it might as well not have.