>>49926955
The hair and the chin stitching have always been the biggest giveaway for me. Bootlegs feel like they get the stitching off pretty often, and it tends to stand out as a result. Official fumo stitching tends to not be the first thing you can notice, even if it's in view. Usually you don't even notice it unless the image is from a lower angle.
Bootleg hair also tends to not be as flat, and looks a bit too much like microfiber. There's also the case of how accessories are handled. Quality can really dip there. The ear tufts and necklace on the bootleg Nazrin are pretty jarring after the official Nazrin got shown.