"When some among them I had recognised,
I looked, and I beheld the shade of him
who made through cowardice the great refusal."
- Dante's Inferno
I no longer have complaints about other players' shade behavior. I used to think it was a pretty weak way to game the game. But real wars have their spies, so it's understandable that they're permitted in this game. And the game is about having fun, so try to have fun with it. With that said, here are my general suggestions on how to have fun with shades:
1. The best way to counter a shade is with a shade.
2. Make your shade known to you fellow countrymen, so if your country needs to pull old painless out of the bag and deal with a shade, they know who to call upon.
3. If a shade is foolish enough to park on a runway or out in the open like Cyrbo is known to, summon a countryman with a known shade, and have them come back for an easy kill. Repeat for as long as you find it fun.
4. If you hear that a shade is operating, but can't find him and you have time to kill, up a plane and do a loop around a field about 2/3 the way out to the dar ring. Then land, save film, log out, and check film to find him. Re-up your shade, and get the easy kill.
5. If a known shade is operating in your territory, can't get a kill due to distance or find him at all, but feel compelled to counter it, up your own shade and share your gathered intel with your countrymen, and with the third country.
6. If a known shade is operating in your territory and you feel compelled to counter it, sink as many carriers and reveal as many missions run by the offending country as possible.
I personally don't condone it, but if they're going to do it, why on earth not have some fun with it? And it turns out that it is actually a good deal of fun.