Assessing the true quality of a sofa requires inspecting its hidden internal construction rather than just its outer fabric. High-quality couches feature sturdy frames built from kiln-dried hardwoods (such as oak, beech, or maple) rather than weak particle board or stapled plywood. Look for robust joinery like dowels and corner blocks, superior suspension systems (such as sinuous steel coils or eight-way hand-tied springs), dense high-resiliency foam cushion cores, and tight, straight stitching on all seams.