Their criteria for an "expert" flair are discussed here: https://www.reddit.com/r/AskHistorians/comments/4p4wl7/rules_roundtable_13_what_is_an_expert_what_does/

Their criteria for an "expert" flair are discussed here: https://www.reddit.com/r/AskHistorians/comments/4p4wl7/rules_roundtable_13_what_is_an_expert_what_does/ https://www.reddit.com/r/AskHistorians/comments/4p4wl7/rules... As for individual posters, you can probably just message them and they'll be happy to provide their background. If not, I'm guessing you can message the mods and ask for some proof that they are who they say they are.