Duvet cover vs. comforter set: Duvet covers need a separate insert. If you're buying for a bare bed, get a comforter set (Feelyou, Erosebridal) rather than a cover-only product (Ambesonne, Lunarable). The listing will say “insert not included” if it's a cover.
Print style matters for longevity: Photo-based prints look impressive in listings and fade faster in rooms. Line-art and illustration-based designs (Ambesonne, Lunarable) tend to age better with changing room aesthetics and after repeated washing.
Dorm Twin XL warning: Standard twin fitted sheets are 75" long. Most dorm mattresses are Twin XL at 80". If ordering a bed-in-a-bag for a dorm, verify the fitted sheet dimensions before buying.
King-size print scaling: Not all NYC prints look good at 104 inches. Illustration-based designs (Erosebridal, Ambesonne) hold detail at king scale. Photography-based prints often compress badly. Check the king-specific listing images, not just the standard product shot.