That Austrian definition of value is great, however I would be suspicious of it being subjective only... might always be both and actual value is on their equilibrium's sustainability (even if pleonasm); and so apart markets can also be understood as subjective since certain angles...
As for what is "signal", it might be reasonable make hand of what is a good "work of art" in aesthetics, those are, the ones that are true to themselves in the way that the mediation between the subjective (artist whatever intention) and the objective (artists whatever technique) has a logic on its own. That can't be faked in works of art, else are known as kitsch works (shitpost?), although within those there could also be works worth of appraisal even if measured with just a couple of sats. Philosophy aside, in everyday life the scam artists are called out wen whatever part of equilibrium gets exposed, for example in the objective "hello I like nostr" that turns sketchy wen followed right away by the subjectively suspicious "gib me zap", in those cases even objective and subjective are replaceable each other, logic all turned around fails to convene honesty on its own
Who knows maybe a folk "follow your hearth" is a valid answer to wen and how much zap, unless the post is objectively true alike "hey folks happened this I need x to reach y, zap asap plz" in which case accountability is reasonable to be summoned
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