Makeup (as it relates to baseball and scouting) can vary greatly even within the same family. Much of it is developed over a long period of time and influenced greatly by surroundings.
Good makeup doesn't have a clear definition. It involves many things. It is possible for someone to have excellent work ethic, great character; even outstanding talent and full of desire... yet come far short of having championship caliber makeup. Then again these things could add to the overall baseball makeup of that player.
Some of the most important things that those with great makeup have is mental toughness, persistence, lack of fear, the ability to adapt, and confidence. There are many other things as well. The guys with the championship caliber makeup are not always the nicest people. Yet it can and does happen that way at times.
Makeup can include most everything that is not physical. Many of those with great baseball makeup could be considered thrill seekers. Sometimes a player can give clues to his makeup based on how he answers certain questions. i.e. Are you satisfied with your ability? What are your goals? Are you a risk taker?
If there is such a thing as great makeup in banking or accounting... It might be much different than great makeup in baseball.