I completely disagree with Caius take on this card, Keen Eye is, without a doubt, the worst "Permanent: spend resources for stat boost" talent in the game by FAR. Not only it doesn't hold a candle against Scrapper, Streetwise and Higher Education (and the fact it's the only card out of these 4 not to get taboo should tell you a lot), but it's absolute ineffective on its own even without considering its class alternatives.
"Now why is that?" You may ask "Why is this card so bad? It gives a stat boost of +1 for and , two of the main game winning skills, for the rest of the turn for 2 resources, and you can even stack it if you have the cash"
And the end of that sentence is exactly the issue: Guardians do not have the cash for this kind of luxury, with possibly the exception of Zoey Samaras, Leo Anderson and Tommy Muldoon, they are constantly paying for assets, put allies in play, play events, they simply cannot afford the economy to leverage on the stat boost reliably. Nathaniel Cho can, given his playstyle is less asset heavy, but his is too low for the boost to matter, and his is high enough he doesn't need it
Second, +1 for 2 resources for all your skill checks in a round is a very bad deal in anything above easy, and very questionable on easy itself. By the time you can afford the exp for this permanent, the stat boost will probably not suffice for most skill checks you will have difficulties to complete. Sure you can spend 4 resources for a +2, but where you are gonna get enough money to do so?!
Third, and this is the reason what leaves Keen Eye completely dead in the water: boosting all of your skill checks in one turn by little is massively inneficent compared to boosting one skill check by a lot, because that means you are committing the rest of the round fighting and/or investigating. Most guardians aren't just gonna spend all of their actions investigating one location, even in multiplayer, they are very likely to want to take other actions in between, before or at the end of their turn, like moving to another location to investigate there. And even the most combat heavy guardian will struggle to do nothing but fight the whole round (unless you are playing a full 4 player game with heavy enemy spawning and high boss health), their turn will probably also be interspaced by moving and engaging.
You sacrifice massive action flexibility to make use of this Permanent, which makes it very difficult to justify using. Sure the times it works (in location with lots of clues and enemies) can be pretty good, but remember you are spending 3 exp for a highly situational permanent and possibly adding to your deck and buying various economy cards just to make use of this
I cannot understate, for a 3 exp card, how bad Keen Eye is, it's almost worthless on its own and ridicolously situational if you have the economy for it. Ironically, if this was the Rogue permanent talent instead of Streetwise... It would still be absolute rubbish, but at least would fit a niche because rogues have various ways to grant themselves additional actions to make the most of the buff