1 Samuel 16:13
God chooses men and women to be His representative on earth. Most of whom seem reluctant at first. Man has been, and always will be flawed. God uses the voices of these selected Old Testament individuals to deliver Gods messages/guidance for living in harmony within His kingdom. The indwelling Spirit gave these individuals authority. Authority was needed to lead the people and steer them back to God.
Psalms 51:11
The Spirits effect on these individuals was to draw them closer to God. Clearly David felt differently with the Spirits presence and begged to keep it. Davids relationship with God was intimate. It can be felt throughout the Psalms. Something interesting to me is that God only gives these individuals enough of the Spirit to proclaim Gods messages and speak with Gods authority. They did not become godhead's. There is still much of their human frailty on display in their lives as they argue with God and commit sins against God.