In Bible times wine and other liquids were stored in containers made of animal skins (read Matthew 9:17). These skins would eventually become brittle and develop cracks, particularly when exposed to the smoke given off by fires that burned in the tents and primitive houses of that time.
The psalmist compared himself to one of these useless wineskins. But even when he felt burned out and unworthy, he found comfort and joy in the law of the Lord.
PSALM 119:83 – I am become like a bottle [wineskin, NIV] in the smoke; yet do I not forget thy [God’s] statutes [decrees, NIV].