When evaluating sofa quality, prioritize kiln-dried hardwood frames (such as oak or birch) to prevent warping. For cushioning, ensure a high-density foam rating of at least 1.8 lbs/ft³ or higher to prevent sagging. For upholstery, check the Martindale rub count; a rating of 20,000+ cycles is essential for residential use, while 50,000+ cycles is required for commercial/contract environments. Additionally, verify that reinforced corner blocks and sinuous springs or Italian webbing are used for structural support.