I am an associate scout. Each ML org is different. The one I work for pays me a percentage of every player I turn in that eventually signs with our org. If they do not sign or do not sign with our org I do not get a dime.
An associate scout works under the direction of an area scouting director. You job as an associate scout is to scout players and then turn in a card on the players you believe an area paid scout should come and see. Sometimes you are directed to go see a particular player and report back on that player. Sometimes you are directed to go to a tournement , game etc and report back on players you see or they want you to see or both.
The harder you work , the more you get out and there and see players the better chance you have of turning in players that will eventually sign. The better you are at IDing players and finding players the better shot you have of turning in guys that may indeed be draftable players. Its easy to follow the ones that everyone knows about. The trick is to get out there and find the ones that are not on anyones radar so to speak. And then be lucky enough that they sign with your org.
I am issued an associate scout card by my org each year along with mlb pass and credentials issued by mlb and my org. I would assume all legit associate scouts are issued the same credentials. If you do a good job it is obvious. The area scouts for your org travel to see the guys you turn in. If they are not quality guys the word gets out pretty quick. If they are quality guys that word gets out pretty quick as well.
My forte has been to get out and see guys that no one is on and then take it from there. If everyone is already on them someone has already turned them in. I try to be the first guy to get on a player and turn him in. I have been fortunate and done pretty well. Of course they still have to sign and sign with your org to get paid. But if your doing it for the money your not very smart.