Quote Originally Posted by sapi
Yeh, I've noticed that as well.

I've seen spies jump to +4 or +5 after completing one simple mission (such as spying on a diplomat), but it then seems very difficult to advance them (if you can at all)
You certainly can. The difference you notice is partially because their GoodSpy trait gains 2 levels, and the progression of GoodSpy is 1/2/4/8/16. So the first 2 points (you get both 75% of the time) give him +2 spy skill. Then you need 2 more points to get +3, 4 on top of that for +4, and 8 yet again (16 total points) for +5 spy skill. So it advances you into an area where it becomes more difficult to get stat increases from GoodSpy. Also, only the first success gains 1 point guaranteed (unless you are losing points to BadSpy - the game lets you get to GoodSpy 1 w/ 100% chance of a point on each success). Successful missions after Goodspy 1 only gain 1 point 75% of the time, which makes it that much tougher to score the needed points to have really advanced spies. This doesn't seem too bad though, since their odds go up pretty briskly with each stat point.

I've also found that spies who role low starting skill can be infinitely more useful if you wait for them to acquire an ancillary:

Spoiler Alert, click show to read: 
;------------------------------------------
Trigger beguiling_bard_vnv_trigger
WhenToTest CharacterTurnEnd
Condition EndedInSettlement
and RemainingMPPercentage = 100
and SettlementBuildingExists >= brothel
and AgentType = spy

AcquireAncillary beguiling_bard chance 5

;------------------------------------------
Trigger dancer_vnv_trigger
WhenToTest CharacterTurnEnd
Condition EndedInSettlement
and RemainingMPPercentage = 100
and SettlementBuildingExists >= brothel
and AgentType = spy

AcquireAncillary dancer chance 5


The Dancer grants 2 skill points, while the bard grants 1. Combined, a spy has ~10% chance to get one of them from spending a turn (without moving) in a settlement with at least a brothel, so resting your below average spies is a good way to snag some extra skill points before deploying them, though it does take some time. It could prove as effective to simply throw the spy at a target and crank a new one out if he dies until you get some capable spies around - I suspect which you prefer boils down to what sort of player you are.

Of course there's no need for either of those if you can help your spies pop out with better stats via ancillaries to start with:

Spoiler Alert, click show to read: 
;------------------------------------------
Trigger pickpocket_vnv_trigger
WhenToTest AgentCreated
Condition AgentType = spy
and SettlementBuildingExists >= market

AcquireAncillary pickpocket chance 12


Having a market or above at spy creation gives you a chance for a pickpocket, which is +1 agent skill. If playing a faction that isn't Northern or Southern European, you also get a shot at a pet monkey if you have a market or higher. 5% chance at creation, and it grants +1 agent skill.

So there are definitely alternative ways to go about getting some decent spies if you feel your initial recruitment leaves something to be desired.