>>49926955
A high-quality one will be pretty much indistinguishable to the untrained eye, but someone who's looked at pics of fumos for at least a few months will notice subtle differences in the thickness of the black lines (bootlegs tend to have thicker lines) and their evenness, in the color of their face's fabric (it tends to be paler on bootlegs), in the pattern of the fabric itself (see pic related, although this example is with a lower quality bootleg) and sometimes even in the overall shape of the fumo's body.