The lining — the first thing cut, the first thing you’ll notice
Linings are expensive: extra fabric, extra pattern pieces, extra labour. So when margins get squeezed, the lining is the first to go — or get quietly downgraded to a thin layer that shifts and bunches inside the shell. You feel it within an hour; the garment moves independently of your body instead of with it. Unlined isn’t the problem — unlined done wrong is.
Turn the garment inside out. Look for clean, finished interior joins and tacking stitches at the hem. Raw edges left to fend for themselves are a tell.