I prefer like an ELI25 version, i.e. you can asume that the other person has a major in the university in a technical subject, but not the main topic of the discussion.
It's important that the expert does not give too many details, because otherwise the reply is difficult to understand. Somehow, I think it's easier for me to give good answers about physics than about math [2], because in many topics in physics I already have a simplified ELI35 version in my head, so it's easier to write a ELI25 version.
[1] Whole thread form the original question https://news.ycombinator.com/item?id=33501848
[2] You can't believe in how many ways it's possible to define the Fourier Transform in math, at least 8, and the advantages and disadvantages of each one. Do you want to read a book about that?
I value posts that provide information I did not know that may or may not be actionable in my life. An example here would be the recent dishwasher post. This includes a domain expert stepping in and replying to a post.
I apparently value posts that provide information I already know in an amusing to read format; reposting or retelling of the first post, often. Reminiscent of: "Hobbits delighted in such things, if they were accurate: they liked to have books filled with things that they already knew, set out fair and square with no contradictions."