Building it to higher level you get more scouts per day and higher accuracy.
When you are on some player's profile page, scroll a bit down and you will see "Scout player" bar. Clicking on that you will see if some of your scouts is available, so you can use him. When you use scout, he is away for 24 hours, but you get the report for the player. To be sure that reports is right, you can scout one player several times or even more.
Then, in Menu - Office - Scout reports,
You can see all your scout reports that you have ever received.