The moment cropped trousers made sense to me was a work lunch where I'd worn the same navy pair with flat loafers and no socks, and someone asked where my dress was from. There was no dress. Just trousers that stopped at the ankle bone instead of trailing over my shoe, which apparently reads as more put together than anything I own with a zip on the side. That gap of bare ankle does something out of all proportion to how little fabric it actually saves.
Getting the length right is the whole game, and it is more particular than it sounds. Too short and you look like you've grown out of them. Too long in the wrong way and they drag at the back and lose the point entirely. What works on most people is a break somewhere between the ankle bone and two inches above it, and that changes depending on whether you're wearing them with flats or a heel, so try them with the actual shoes you'll wear, not whatever you had on at the shop. Watch the rise too. A low rise on a cropped leg can shorten you badly through the middle, and a lot of women end up looking stumpier than they are because nobody mentioned that bit. If you're short in the leg, a straighter cut with less fabric pooling at the hip will do more for you than anything cut slim through the thigh. If you're tall, almost any crop looks deliberate rather than accidental, which feels unfair but there it is.
Where they properly fall apart is wet weather and anything formal that needs a long, unbroken line, like trousers under a coat on a cold commute, because that gap of ankle is the first place the cold gets in. They're also not the ones to reach for if you want to look taller for an occasion. A good pair holds its shape through a wash without the hem going soft and wavy, the kind of flop that makes them look like leggings that gave up halfway. Cheap ones lose their structure at the knee within a few wears, bagging out in a way that no iron fixes, so look for something with a bit of weight to the fabric and a proper finished hem rather than a raw or rolled one that will fray the first time it catches a bag strap. A lining through the seat and thigh is a good sign too, it stops them going shiny and keeps the shape honest after a season of actual wear.
Try them on with bare ankles and the exact shoes you mean to wear, because an inch either way changes the whole line.