Janis Joplin Prayers VS Real Prayers
Janis Joplin
There is only one kind of prayer that is good; a prayer in line with the will of God.
1 John 5:14
This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us.
Notice it says if we ask according to His will He will hear us. This implies that God isn't especially interested in prayers that aren't according to His will.
Janice Joplin prayed for a Mercedes Benz. This is not the kind of prayer God is interested in.
I don't know if she ever got one but if she did I doubt it came from God.
If you want to know God's will read the Bible. If you want to know God's heart memorize the Lord's prayer and the Psalms of David. If you want to know what is on God's mind read the book of Romans. Model your prayers after the teachings of the Prophets and Apostles and your prayers will actually get answered. Of course, you also have to mean what you pray; that's the hard part.
"He hears us" is a metaphor. God always hears every one of our prayers. I see no point in repeating the prayers of others. Especially the Psalms. Many of David's prayers are evil prayers. They consist of "kill my enemy and let his children starve to death in the streets". The Psalms are a model of someone taking everything to God whether it's good or bad.
I don't think the prayers of David are as simple as you have them. Regardless, praying the will of the Father is the only way a prayer will be answered.