I think the basic issue with scout, is that scout needs to scan 5 cards rather than 4 to be reasonable. Note that what scout effectively does in most situations is 1. reorder a few cards of your deck (which, without a draw ability is not that great and, even with a draw ability is pretty mediocre) 2. clear out junk from your deck. Unfortunately in order to gain any cards from scout, your deck needs to have a green density of 25% which, by the time you've finished your second reshuffle it is probably a bunch below. Even if you have a green filled deck (say, 40%) scout ends up drawing on average 1.6 cards, or half a lab in a green heavy deck. In order to get a lab effect you need an outrageous 50% green deck. (for reference, caravan gives you a lab effect, with the downsides of being a duration, at the same price point of 4, while durations do have significant downsides with missing the reshuffle, 50% green is way to damaging to achieve beyond the very end of the game to make it at all reasonable). With 5 cards the amount of power the card gives you (how much better than +1 card, +1 action) increases substantially. In a 30% green deck, scout becomes 2 and a half times as strong, still not great but good enough to use. with sifters/crossroads/kingdom vp cards in general. I would begin to view scout as a tolerable option. Adding on the functionality of curses, as some have suggested, would buff up scout tremendously in curse games, I'm not sure I'm comfortable with such a blatant disparity in use, though I understand that the same disparity exist with farming village. In short, scout with 5 cards becomes a usable card FAR more often than with 4, buffs beyond that should probably experiment with drawing 5 first.
