I think for most..with even a "stock" TC or BK that even the well studied watch enthusiast couldn't tell as it sits on your wrist. If they get up close and look at it or hold it then yes, just looking though and it'd be a hard tell. Add a gen crystal, insert and crown and you'd "fool" 99% of the public at a glance. Like others said and I've said before...I wore a BK GMT IIC for a month which has a few obvious tells even at a distance and lately a WM9 16610 with gen crystal and insert and not so much as a look. One person (male flight attendant) said "nice watch, I wish I could afford a rolex." That was the extent of it. No one else so much as acknowledges that I even wear a watch...they simply don't care.