So much of this depends on the physical that I have to bore you with appearance stuff first, it's important:
I'm totally out of the closet to anyone who would benefit from the knowledge and I've slowly started dropping my masculine guard over the last three months. I am 5'5'', 141 lbs, slender, a soft voice, and talk with a lot of facial expressions and gestures. For three months I've let my hair grow from 1/2" to 3" long (and it waves so hard it curls). I have a masculine jaw, a little T exposure skin damage, beard shadow; feminine eyes, nose, forehead, and (not so masculine) chin. Okay enough, well documented. Just setting a mental image.
I was working a big time wrestling event at one of my part time jobs and we all got issued the exact same blue shirt (yes! neutrality! Boo! Bad color!). They also allowed me to wear some of the wrestling sleeves that are made of silky, shiny, red material. The kind that extend from the elbow and form a half glove that your thumb sticks out of. My stand manager knows about me and
had to ask if they made me feel pretty (I did sell them to many pretty girls that night), of course I said yes

Also: I was working in a way that customers had to see my hands up close, and I was wearing clear nail polish.
I just entered strange territory:At several points during the show I got the weirdest feeling that I was not passing as male. Not in a traditional sense, in the sense that the ephemeral thread that males link between themselves: The "Hey dude! What's good? Oh! Look look at her, damn..." type of inclusion was finally, completely gone. One customer told her son that, "She (meaning me) needs the card so you can pay for it," then did a double take, looking fearful as though I would take offense. For the night I felt like I was living between genders, not even on HRT, and it was odd.
Now, I'm MTF and I'm good with that. I identify as a woman that was born physically male, and as a result has had tons of male experience. But I was trying to pass as a man, and I was keenly aware that I did not totally succeed. This was weird. Affirming, but it felt so strange to be exposed to thousands of people like that, have them take some gender biased notice, and not have any of them make any fuss about it. I felt that this would probably help me connect with those who identify as androgynous, or even, on some level (especially early stage), FTM's. I thought that if I take note throughout my transition I could probably tap a breadth of identity experiences, not that I would try to speak on their behalf, but it would make me just that much more of an understanding person.
I know it's not about a MTF passing as female, but I think this experience was important. So strange and eye opening.