How important are appearances, really?

Like every other grad student in history (I imagine), I have mixed feelings about my advisor. There are lots of things about him that I respect, and there are many ways in which he's been an immense help to me, but there are an equal number of ways in which his existence makes my life hard. He's a stubborn, blunt guy with a very loud bark, and sometimes that works for you, sometimes it works against you. But one thing I have always admired about my advisor is the fact that he's never told me I had to look or act a certain way to be taken seriously as a scientist.

When I first joined this lab as an undergrad, I had pink hair and two facial piercings. Of that, all that is left today is my lip stud, but it was my own choice to get rid of the pink hair and the eyebrow ring. I think about my lip ring about as often as I think about my earlobe, because by now it is just another part of me. I forget that I have it, even when I'm looking right at it. And every so often someone will behave oddly around me, and it isn't until (much) afterwards when I realize, oh, they were probably reacting to my piercing. It isn't often that it happens, but often enough for me to wonder what the hell is wrong with people. People have enough trouble taking young women seriously as a scientist to begin with, and if you throw non-traditional facial adornment into the mix, who knows what they think.

But, my advisor took me as I was, and when it came time to attend conferences and present research, he never asked me to take out my piercings to change my hair color. He told me that the work can and should stand for itself. It makes me wonder... the idea behind scientific communication is that it shouldn't matter who does the research as long as it makes a sound argument backed up by good data and factual analysis. However, scientists are human beings, and often the knowledge of who does what piece of research can change our opinion of that research. If some old dude passes by me standing in front of my poster at a conference, he's going to make a snap judgment about my work based on the fact that I'm female and my appearance. He may or may not realize that he's doing it, but he does. I always wonder what people's motivations are when they approach me. Are they actually interested in my work, or do they just want to find out if I know what I'm talking about?