I find that I never build scouts in the early game. They're not cheap enough to justify giving up a slot that could be a slinger. Warriors and slingers do the early game scouting well enough, and are far, far more combat capable. Scouts gain experience from discovering natural wonders, but it's too minor of an advantage. They're never going to gather enough experience to get to that +20 combat strength promotion, which is the only thing that'd really make a difference. Using the Double Experience for Scouts (Survey) policy could help that, but there's no way I'm forgoing +5 against the barbarian swarms. The camps aren't so bad, but if they spawn a wave, particularly a horseman wave when I'm still fielding warriors and archers, I need everything I can get. Even as Greece, I'd rather use the wildcard policy slot for something else, like Great Prophet points, cost reduction on units, or doubled initial envoys. I find the only time I build scouts is when I've advanced to Archers and Swordsmen. At that point there's a much more significant price difference, so they're good then when I want something cheap and disposable.