Most guys would think you were trying to prove a point by dressing only in one style, a kind that is considered as you yourself put it alternative. Lots of guys would assume you would only/or prefer to go out with guys who are more like you. So to be honest I don't think I could see myself going out with a girl in full goth (or whatever it is) dress all the time. It would just look strange (as a couple I mean). Unfortunately if you dress in a way people consider different to the norm then you will be looked at differently. Just the way it is.
Like attracts like. If you have a certain style, you will attract others who like that style (or have the same style). I would say the majority of mainstream guys might not find that as the most attractive style in a girl. Nothing wrong with it, it is just based on personal preference and what kind of guy you are trying to attract with your presentation.
Find out what kind of guy you want and present yourself (the way and with a style *you* like) to get that kind of guy. Most guys like girls with a more mainstream femine style traits and dress (not saying that look isn't feminine, but I think you understand what I'm saying). The hot-girl-next-door style (this is the look playboy strives to have in their models) usually works often on mainstream guys.