So spies can detect other spies, supposedly...but none of my spies ever have. Had an oil well blown up once during wartime, but when my spy got down there the next turn, she didn't find anyone.

How do spies detect other spies? And how can I tell if there are spies right now in my cities, just like mine are in theirs?

Remember the AI could have set themselves there. Waited then Destroyed then ran. Or they could have just disbanded the spy. I also believe that although your spies can see other spies they cannot "stop" or detain other spies although greatly reducing the odds of a mission's successfulness.

So if I park a spy on my only aluminum resource, it's less likely to get blown up?

Post soldiers on the resource too. I believe that lowers the chances as well.

post a spy and oodles of units on the strategic resources,

it SUX having your lone oil well blown every time it gets rebuilt, 8x in one friggin game argh

You can "never" see a spy, even with your own spies about. You can catch them in the act and having a spy at the location along with troops help increase the odds.

The reason why "never" in quotes as I have seen a bug where if you have "see all friendly movement" turned on, sometimes you will have the display move to a location and follow a unit that is not visiable. Of course the next turn, the resource (where the display focused) gets blowed up.

I've also had situations where a chinese spy was visible from my military advisor

I've never seen the AI use spies. Probably too complex a task for them.

Was your mine hit by aircraft?

I've never seen the AI use spies. Probably too complex a task for them.

Was your mine hit by aircraft?

Nope, I can guarantee that the computer can use spies. On monarch difficulty, I had my oil well blown up multiple times. Each time it happened, I was told that it had been destroyed due to sabotage, so I know that SOMEBODY was using spies, and I have only played SP games. Thus the 'puter was using spies:scan:

When all else fails, manipulate the data! -- (Can anybody tell me if this is attributed to someone?

Well, according to Google, it originated from some guy named Anon. :mischief:

the more soldiers you have on one square the less chance that I spy will succeed