Single Scout Scouting
Using a single scout to scout your enemies is a common technique to obtain critical information without risking almost anything.
Most the time when you do this it is a check to see if your opponent's gates are open. It's fairly simple. If your opponent has any scouts at his city and has his gates open your scouting mission will fail. However if he does have scouts and his gates are closed you'll have a successful scout and get a report of his city where you see he has scouts in his city. The final option is where your opponent has no scouts, your scouting mission will produce a report but there is no current way to see if the gates are closed or open.
Quite often when you scout someone with a single scout they will scout you back. Sometimes with quite a few scouts (90,000 or 100,000). Thus if you have 130k scouts or more you can overpower him and kill off his scouts for half the cost.
Finally it's always good for a laugh when you scout many targets in an alliance. Tends to get the alliance chat going and get them worried you are getting ready for an attack. Watch them squirm!