When evaluating flare jeans, focus on fabric composition, specifically the ratio of cotton to elastane (spandex). For a premium fit, a blend of 98% cotton and 2% elastane is standard for comfort stretch, while 100% cotton is preferred for authentic vintage styles. Pay close attention to the fabric weight, measured in ounces (oz); 10oz to 12oz is ideal for four-season wear. Additionally, verify the wash process (e.g., enzyme wash, stone wash, or acid wash) to ensure color consistency and shrinkage control within a ±3% margin.