Not sure if I have understood questions well, but I will give it a try anyway.
For me, on any social media, the answer to the question "who do you believe" is based simply on this person's real life acievements.
If I look for gardening advice, I want to see this person's garden and harvest.
If I look for advise on RMH, I want to see this person's stove.
If I look for a permaculture design advice, it would be nice to see some of designs, etc.
Sure, metrics mentioned above are nice and all, but not as strong as proofs of what the person really accomplished in order to be a source of credible information and authority on the topic. SKIP would be the closest one, but it is not exactly what I'm looking for.
Exaggerating - that's probably why Paul values Sepp Holzer so much and gives him a 10 on his Eco Scale, right? :)
"What are the values of each person?" is a bit more difficult. One can be a great gardener, builder, designer, and an a-hole. Here, I simply tend to believe more these people whose values seeem to be closest to mine. Another story is to know whether what you read on the Internet is true in real life, and that's where the metrics suggested above can help.
In my opinion these metrics surely show the level of engagement of the person on permies forums and in projects. I can say that it is positively correlated with willingness to help, and guarantees civilized discourse.