But I can certainly seeing it played to the accused favour by the counsel saying something along the lines of: "She was drunk enough that during consensual intercourse, she threw up."
Thereby sidelining that issue for pretty much the rest of the trial. Even if it's ever brought up again, in the Jury's minds, it wouldn't necessarily have the negative connotation that you're envisioning.
[1] “because he is easily recognizable in a photograph showing him raping the victim while she is visibly ill… why the RCMP decided these photographs aren’t evidence of rape is beyond us.” http://www.salon.com/2013/04/12/anonymous_on_rehtaeh_parsons...
I'm not saying that Rehtaeh Parsons was not raped; only that when the police and prosecutors say that they do not think they could secure a conviction, I'm inclined to trust their expertise and knowledge of the case.
PS. A generic question. Not related to the crime mentioned in OP.