People usually bring up Blaire White as an example of a trans-woman that passes, but we're only familiar with her from YouTube videos. If we met her IRL, I wonder how many people would still think she passes.
@alyx I have been with enough trans girls that I can tell pretty much now. It's not even conscious. It's a gut feeling. I can just tell when someone was born with a pussy or cock, and very rarely am I fooled. It's not just face shape or body shape, it's also facial expression and posture.