To identify high-quality cotton shirts, look for medium to heavy-weight fabrics with a tight weave, such as Egyptian or Supima cotton, for durability and smoothness. Check for evenly spaced, tight stitching, especially along buttonholes and seams, and ensure buttons, collars, and cuffs are made from durable materials like mother-of-pearl and feature reinforced stitching. Feel the fabric for a soft, smooth texture that improves with washing. Finally, ensure the shirt fits well, with a balanced cut that enhances your silhouette without transparency or awkward draping.