Even in my best moments, I sin.
When I praise God, I do it mostly for things He has given me. My praise is not so much rooted in his character but in his giving me what I want. In such instances, my real god is not God Himself, but my own ease and pleasure. He gets my praise for catering to me, which reduces Him to little more or else than a means to my ends, a mechanism, a utensil, an instrument.
At the beginning of his Institutes, Calvin righty insisted that real wisdom consists of two things, knowledge of God and knowledge of myself. In my sinful prayers they both emerge. I learn that, at my best, I am wicked. I learn too of God’s infinite descent and mercy, which graciously accepts praise even on that fetid basis.