When evaluating raw feathers, the most critical factors are cleanliness, down content (for waterfowl), and structural integrity. Buyers should ensure feathers have undergone professional sterilization and dust removal to prevent allergens and odors. For decorative or craft feathers (like ostrich or peacock), the plumage density, length uniformity, and natural luster are key. Always request a specification sheet detailing the species, size range, and whether they are 'hand-picked' or 'machine-sorted' to ensure they meet your specific application needs.