That was an old joke I learned as a kid. An "ex" is a has-been. A "spurt" is a drip under pressure. So an "expert" is a has-been drip under pressure.
Everybody's an expert at something.
You will come across readers who know more than you do about things you're writing. You will also come across people who THINK they know more than you do, but don't.
You do your research (or dig deep for your own authentic but unique experience) to please the former, and that sets you up for criticism from the latter. Sometimes you can even see it coming before you start to write....
I have been reading Punch magazines from the WWI era this week, which is the era which inspires The Misplaced Hero. The series will take place in an alternate world, which is based on the adventure story or silent movie version of reality of the times. Since it is an alternate world, I can mash things up all I want, but since it is a time of cultural shift, I do feel the need to adhere to a certain chronology.
For instance, we'll likely first meet Lady Pauline at a Suffragist rally. She will be a daring and modern young thing -- a proto-flapper. But of course, it's too early for her to actually BE a flapper, because that's a part of the whole post-suffrage state-of-mind, isn't it?
I have come across at least three references to "flappers" in 1914 jokes and cartoons so far. And yes, the word seems to apply to wild and daring young women. In one case, the reference implied loose women (i.e. a man spending all his money on partying and flappers) and another to a flapper as a star struck young groupie, seeking autographs of the famous.
Not sure I'll ever need to use the word "flapper" specifically. Still, I find it ironic that even though I now know it's a common 1914 concept, I feel more comfortable using it in a fantasy world than I ever would in a realistic fiction of the time. (After all, I would have looked askance at someone who used the word "flapper" pre-war.)
I guess what William Goldman said really is true: Nobody knows anything.
See you in the funny papers.