Having been here for a good while, gotta say that:
99% of "spy" accusations are completely groundless, with almost all the busted missions happening because the enemy can read a map, or because in a crowded arena somebody ran across the mission by dumb luck.
90% of those screaming about spies don't themselves have enough map interpretation skills to make the kind of logical deductions Getback ilustrated -- so they can't see how anyone else could figure it out either. They also overwhelmingly tend to be...ummm....unseasoned players.
90% of missions "at risk" (publicly announced) are so poorly planned that they're not worth joining in the first place. Anymore, I'll go with a group if I happen to see them upping, and I know they know what they;re doing (A hearty to the AKs, for example).
I'll side switch to find a fight, but (like Guppy) am just looking for fun -- and like Guppy (when his wittyness switch is turned off), I'd consider revealing mission info unsportsmanlike. We play for the game, period -- and if something makes the game less of a game, why do it?