pfarland:
I do want to say that sometimes you have to be overly picky for the good of the game. I have a military themed game and I require that the players have either experience in or with the military. I've seen WAY too many players that try to play or run military themed characters or games and have no clue how to do it believably. And it's usually not the ones that are upfront about not knowing, it's the ones that THINK they know how things work because they've watched a lot of TV and movies. I would much rather turn down a bunch of otherwise good players because they don't know at least the basics of the military than to let one in that thinks John Rambo was a decent depiction of what a Green Beret is like.
I would much rather have a GM that is picky for the good of the game, than to let in players that will destroy the setting because they can't play a believable character. It's why I don't even bother trying to play any medieval games, I can't get into that mindset.
While I don't question the right of anyone to run a game as they see best, nor am I asking anyone to change their modus operandi, I'm going to be pretentious for a moment and say this mindset seems somewhat antithetical to the idea of roleplaying.
The whole idea is that the player should place themselves in the role of that thing rather than actually be that thing, when you insist the player already be that thing, there's less role to assume.
If there's a point or benefit to roleplaying, it is finding empathy for someone or something that is fundamentally different from yourself in at least one way. It's taught me a lot of tolerance for people who aren't culturally, philosophically or biologically the same as myself, personally. If you aren't stretching at least a bit to be that character, why are you playing that game as the player?
Sure it's going to be hard for someone who doesn't know what the actual military is like to speak correctly, and I certainly understand people pretending to know something they don't is frustrating, but I can't wrap myself around this mindset.
Not to mention someone who served in a foreign military or in a different decade from the GM's reference pool is still going to be "wrong", no matter how authentic the player may be.
What's really important here, each player getting the exact slang terms correct, or players learning what it's like to have to follow orders that could very well kill you to little or no appreciation?
I just find this criteria bizarre. What if I want to run a game of Drow conducting political intrigue among each other? Do I insist on all female players since all the major movers in that society will be women? Or do I have to insist on actual dark elves only applying to that game?