Nutrition scientists disagree. Politicians and political scientists disagree. Psychologists and social scientists disagree. Now that we know we can be looking for high-quality contrarians in those fields, how do we sort out the high-quality ones from the lower-quality ones?

What's your proposal for how to do that, aside from just evaluating the arguments the normal way? Ignore the politicians, and we're basically talking about people who all have PhDs, so education can't be the heuristic. You also proposed IQ and rationality, but admitted we aren't going to have good ways to measure them directly, aside from looking for "statements that follow proper logical form and make good arguments." I pointed out that "good arguments" is circular if we're trying to decide who to read charitably, and you had no response to that.

That leaves us with "proper logical form," about which you said:

Proper logical form comes cheap, but a surprising number of people don't bother even with that. Do you frequently see people appending "if everything I've said so far is true, then my conclusion is true" to screw with people who judge arguments based on proper logical form?

In response to this, I'll just point out that this is not an argument in proper logical form. It's a lone assertion followed by a rhetorical question.