Muse on this, guys.
Within the first seconds of meeting you, a girl knows and has decided if she's willing to give you a shot or not, if she's willing to give you access to her time and attention or not, if she's opening the door for you or not.
If she isn't, there's nothing you can do, be, or say that will make her change her mind and her feelings UNLESS either you disappear for months or years and when she sees you again she likes what she's seeing, or you suddenly reveal yourself to be Elvis in disguise that makes you reevaluate you a whole other way. But if you weasel yourself into a friendship with her, who is she to tell you to bug off (unless of course your presence would be a blight to her situation if you are really that hard on the sight)? She'll take what you give her for free.
It's a matter of her feeling you, or her valueing you as a sexual partner. Physical attractiveness is one element over many others, and sometimes not even an element : how you dress, how you look, how you speak, how you smell, how you walk, what you demonstrate as you move, what you say, what you promise, what you suggest, etc. In fact a lot of times objective physical attractiveness counts for few if at all in the feeling of attraction itself - although it does help.
That's why girls say often it's not a matter of whether he is attractive or not, but if she IS attracted to him or not. It is a feeling based on instinct. They don't think, feel, and work on this like us men do. We men are wired in such a way that if we see an attractive woman, we have the biological urge to render her pregnant within seconds of seeing her. For women it's not how it works, at all. However, because of how we males see sex and attraction it's way too easy for us to present women's attraction as "them wanting only hot guys/bad boys/good-looking jerks". Maybe they do for a fling, an affair, friends-with-benefits relationships, or a relationship until she founds a better deal, but not for a stable, mature relationship that she hopes it'll last for years.
Physical attractiveness only helps woman open her doors to you and invest in you easier. You still have to talk to her, get to know her, and make her develop her willingness to follow you, either for a relationship or even for a straight one-time hook-up. It also depends on what she's open for right now, if she's ovulating or not, if she is intoxicated or not, what is her current mood or status, if she's pissed at her boyfriend or not, if she's with people she knows or not, etc.
Truth of the matter is, for relationships at least, often they don't mind as long as you look good enough for her to open her doors to you enough that she might like what she hears from your lips. For casual sex however, it's another issue.