If an adult gets spoiled, it usually means that they are treated so well that they come to expect to be treated that way all the time. If you tell someone "You're spoiling me," it is a joking remark, meant to make the point that they are treating you very well. If someone get's spoiled, it means they expect to be treated in a special way all the time. If we say a child is spoiled, it is not a joke. It means that they have been given special treatment and no discipline, resulting in a child that is demanding and misbehaves.