Drawer construction is the clearest tell of quality in a bedroom set. English or French dovetail joints — the interlocking triangular cuts at each corner — are hand- or machine-cut and hold under repeated use for decades. Stapled or glued butt joints are faster and cheaper to produce and are the first thing to fail, usually at a back corner, within a few years of daily opening and closing. Pull a drawer fully out on the showroom floor and look at the corners before you look at the finish.
A bed frame's real load rating matters more than its looks. Look for a center support rail with a mid-span leg (not just side rails and headboard or footboard brackets) on anything queen size or larger — without it, a frame can develop a sag in the center slats within a year or two, especially under a heavier mattress or two people. Metal bed frames should specify a weight rating in the spec sheet; if a store can't produce one, ask them to find out rather than assume.
Nightstand height should sit roughly level with, or slightly above, the top of your mattress — a nightstand well below mattress height is a common and easily avoided mismatch. For storage pieces bought to last, metal drawer glides (side-mount or under-mount, rated for smooth operation under load) beat wood-on-wood glides, which stick and wear with use; ask to open a drawer fully loaded, not just empty.
Bedroom sets are also where "ships assembled" versus "assembly required" varies most by piece — headboards and footboards almost always ship in parts, dressers usually arrive assembled or nearly so. A store that tells you this upfront, rather than after delivery, has thought about the full experience, not just the sale.