Most of experiences have been that people either don't notice, don't care, or if there's a negative response, it's discrete (be it at the mall, coffee shop, Panera, etc). That's all good, and as I get more confident I find I want to embrace the role of ambassador (as long as it is in safe public places that is). Here's one story though from a few years ago that was a negative experience at the time but looking back I wish I would have had the confidence to handle it differently.
I am at the mall, I enter in through Macy's and then go into the main mall area. As I recall, it's fall, I'm wearing a plaid skirt that hits just below the knee, brown boots with a modest heel, and a sweater. The first kiosk inside the mall is a group of three latino males (I only mention that detail because their style was macho) selling specialty hand lotions... They see me and start cutting up / laughing a little bit. I held my head high and just kept on walking. The only thing I remember hearing as I walked by was "blah blah blah, hombre." I wanted to say to them... "dude, your selling hand lotion!"
So I shop for an hour or so, and the shortest walk back to my car is past their kiosk again. They see me (still kind of giggling but toned down), but one steps forward to try to sell me hand lotion. I give him a "screw off" look and kept on walking into Macy's. Now to my point - looking back, if I had been a little more confident, I should have engaged him and listened to what he had to say. It could have been an opportunity to portray us in such a matter that the next time someone like me came by the booth, they'd be a lot more cool about it, especially if I had bought some product.