(I guess I'll mention again that I wear my hair down and don't do much with it beyond brushing. 🙂 )
I'll start off again by saying that yes, of course, there's no way to know what total strangers are really thinking. Basically, I totally agree with Cat on this one; people see what they want to assume, and there's no point in driving myself nuts wondering. Usually, though, friends, acquaintances, coworkers, etc. will come out with it eventually, if only behind our backs... and I'm so sorry that you've had that experience from people who were so cruel.
I've thought about this some more, and I've realized that for me it comes down to the fact that middle-aged women are invisible. We don't get stares or smirks or second looks. I know I'm blending in (and I use that term deliberately, because my greatest goal was not to stand out from the cis population) when nobody pays attention to me at all. People are polite, but treat me as unremarkable and don't do that double-take thing.
I also find myself in situations, albeit blessedly less and less, where like Kelly I have to tell people I transitioned because my old name popped up on my mortgage or credit report or tax return, and they either argue with me that they need my "ex-husband" or they get this poleaxed expression and cannot absorb the information. Bank tellers will not be polite to the point that it takes them 15 minutes of struggling and failing to grasp the idea that I changed my name. 😉 I've nicknamed it the "blue screen face" because they just shut down completely for a minute trying to cope with this thing that's totally outside their experience. It's annoying and frustrating, actually, but it does establish that "used to be a man" or whatever is not percolating easily through their minds.
All bets are off, of course, when someone already knows the story, so the real problem is people who out me behind my back. I like to be in control of when and how that story is told, but I'm not surprised that gossip sometimes overrides common sense. And *then* I will occasionally hear about someone who learned about my past and decided to say something nasty when I wasn't there.