This is becoming less and less of a problem for me as time goes on, but I have found that when I appear male, people almost seem to go out of their way to project their own views of what's male back on me, almost in spite of whatever "feminine" clothing or behaviour I might have. Like maybe they think that I don't realise how girly some of the things I do are, and they're embarrassed for me and want to help me feel like i'm a guy.
For example, I went to a salon once when I already had long hair (but still looked obviously male) and I brought a picture from a magazine of a girl who had what I guess would be considered a pretty feminine haircut. I asked the person to make my hair like that, and she was perfectly nice about it (didn't even blink)... but she didn't make my hair like that at all. What she gave me was a very clearly "male-ified" version of what was in the picture. Evidently she couldn't fathom that, being a male, I really did want it just like the picture, unless I went out of my way to spell it out for her.
So... take that as you will.