A good pleated dress has that slight crunch to it when you pick it up off the hanger, a sort of papery resistance before it settles and falls into those neat vertical lines. You can feel straight away whether the pleats are sewn in to last or just pressed in for the photograph on the hanger, because the cheap ones go soft and flat the second they touch a warm hand. The ones worth having almost spring back.
Size these by your shoulders and bust rather than your waist, because the pleats will do a lot of forgiving lower down and you don't want to end up swimming in fabric to accommodate a fit through the chest that was never right to begin with. Watch the waist seam on any dress that claims to be fitted there, since pleats can hide a seam that sits two inches too high or too low on you, and you won't notice until you've worn it all day and it's bunched up under your ribs. If there's a tie or elastic waist, try sitting down in the changing room, not just standing in front of the mirror, because that's when a badly placed seam makes itself known. Hemlines matter too. A pleated skirt that hits mid calf on the model can hit your ankle if you're under five foot four, and the pleats make that length read even heavier.
The difference between a dress that earns a second season and one that dies after a few washes is almost entirely about how the pleats were set. Heat pressed pleats on a synthetic blend tend to hold their shape through a cool wash and a gentle tumble, whereas pleats on a cheaper viscose can drop out within a month, leaving you with what is basically a shapeless tent with memory of better days. Check the stitching at the waistband where all those folds gather, because that's the stress point, and loose threads there are an early warning. A lined skirt section is usually a good sign, since it stops the pleats clinging to tights in a way that looks faintly tragic by lunchtime.
Where this shape lets you down is anywhere you need to move fast or sit for hours in a tight space. Pleats don't love a packed train or a long car journey, they crease into the wrong places and need a shake out before you're seen in public again. They're also not kind if you're pear shaped and choosing a style that pleats from the natural waist outward, since that can add width exactly where you don't want it.
The best ones move when you walk, a proper swing rather than a stiff sway, and that movement alone makes getting dressed feel like less of a chore.