Just to add to what Steph's saying, a few times I've helped drunk women find their way to a cab when I've found them all but passed out along the High Street. Had I been predatory in any way then.... well I don't think I need to go there.
Whilst being out and drunk isn't "asking for it", being in a fit state to look after yourself gives you a lot better chance of not becoming a target.
The missus will kill me for saying this but there have been times when we've been out drinking she'll ask what we did when we went to bed

and genuinely have no recollection of what happened even though she seemed completely with it at the time and was able to make quite specific demands from me
Gone off on a bit of a tangent here but I understand where you're coming from Steph.
No one deserves to be raped/attacked, however there are steps you can take with regards to your behaviour and appearence to make it less likely to happen.
Not really a lot different to a bloke walking around late at night on his own behaving in a particular way to try and avoid being beaten up by a gang of thugs.
No one deserves for that to happen to them, no one asks for it to happen but it is a reflection of the World we live in today.