No one cares if you wear headphones. You're a jerk if you order coffee with earbuds/bluetooth in. I've never seen anyone flip up a Google Glass to the top of their head to have a conversation, but if that was standard behavior, Google Glass would be widely accepted.
The problem today as I see it isn't the camera ($diety knows tourists take enough pictures of you in SF), its people (influenced by clueless Google marketing) being smug and oblivious enough to keep the Glass on during normal human interaction.
The idea of a google glass that can be temporarily disengaged (flipped up) is a really interesting one. It seems like that gives the wearer more control over where they would like to direct their attention. It also signals to whoever they're dealing with that their attention is undivided.
This is probably the single biggest difference between headphones and google glass. I wonder if the designers at google will figure that out.
The problem today as I see it isn't the camera ($diety knows tourists take enough pictures of you in SF), its people (influenced by clueless Google marketing) being smug and oblivious enough to keep the Glass on during normal human interaction.