Disclaimer: I'm not qualified to offer a truly informed opinion on this subject. I am neither a researcher of sexual identity and gender, nor a lesbian, nor a woman. But I can calls 'em as I sees 'em.
It seems to me that people are people, everyone is different, and one cannot tell just by looking at how a woman dresses or wears her hair and/or makeup whether she is predisposed to a given sexual orientation. That being said, one might postulate that the woman who rebels against the conventions of appearance and behavior might also be more open to "unconventional" forms of sexual expression or identity. My own sexual identity, though, does not support this hypothesis. I prefer to maintain a masculine identity, and I am attracted to men with a masculine identity. But I am a man, so that point is likely irrelevant.
I do know that of the lesbian women I've known, more seem to prefer a less feminine appearance, both for themselves and in the partners they choose. Again since I have known (more than just in passing) relatively few lesbian women, this is not a qualified statistical analysis. Just a personal observation. If we're talking only about lesbians here, I would be surprised to discover there are as many feminine lesbians as there are "butch" lesbians. Lesbian women seem to dislike the "lipstick lesbian" look. But my own experience also tells me that women will have varied individual attractions to women just as anyone else. Some men prefer tomboy-looking women. Some men prefer feminine-looking women.
I think the "butch" look is a way for some lesbian women to express themselves in a way that is unconventional, as is their lifestyle. There are at least three different dynamics here. Sexual orientation is how one views their personal sexual and romantic attractions. Sexual identity is how one views themselves in terms of where they stand on the lesbian--->straight chick spectrum. And gender role is how one behaves relative to the conventional definitions of male and female behaviors. Other people will have opinions on whether and to what extent they think another person is lesbian, bisexual or straight, but I give credence only to how a person identifies their own self in this respect (unless they're totally in denial... straight guys who love cock). But there are plenty of women who, for whatever other reason, might discard the "girly-girl" appearance to project power or strength, or to send some other message. And there are plenty of women who simply prefer to be in comfy clothing and keep low-maintenance hair. Who says a woman can't mow the lawn, or fix the car, or build a house? Oh wait... I know who... men! I don't see how a woman's expression of her gender role has any relevance to her sexual identity at all, so I'm ruling out the notion that woman who mow their own lawn are predisposed to a lesbian sexual identity.
On this next point, I am straying from my comfort zone, and offering a totally biased opinion based on my life of observation and not on participation or even qualified study.
People make a lifestyle choice when they identify with a given sexual identity. Straight people largely act straight. They can do that because it is perfectly accepted to be straight. Non-straight people can choose to act or look straight, identifying with the straight community, or they can act or look gay, identifying with the homosexual community. This "homosexual community," however, is an apparition. To straight people, it is the "other" in terms of how they view homosexual people. To homosexual people, it may also be the "other" in terms of how they view themselves relative to straight-acting people. We all know it when we meet a "flaming homosexual" man. But I've met men who were quite effeminate, and who were also quite heterosexual. To homosexual people, the "gay community" might also mean the "us" in relation to the "them" of heterosexuals. So here's where we see stereotypical appearances and behaviors that we identify with "straight" and "gay." It means nothing, really, because in the end, people are people and we're all different. I'm just about as queer as they come, and if you met me you'd never guess it.