We all have value in the Lord Jesus Christ. Others may reject us but He will always love us. As Mary approaches Christ, the lyrics don't say she "went" to him, she"came" to Him as He calls all his children who listen to his Word. Read Luke 7: 35 to verse 50 and you can see that this prostitute, an untouchable, gave to Christ what the wealthy Pharasies host did not give him. Nor did they know the blessing she received as he washed away her sins because of her faith in him. No one knows the cost of the oil or her pain nor the love she received from Jesus that moment. The metaphor is we can pour our praise on Jesus and our own personal sin can be washed away as well, and that is between Jesus and us. No one knows the cost of that but the individual and Christ.