Just been googling and I don't know if this is the study responsible for planting the thought in my mind, but I found a 1999 study by Acierno, Resnick, Kilpatrick, Saunders and Best published in the Journal of Anxiety Disorders. They seem to be prolific authors in established American science journals, along with another author called Clum, so I think their studies would probably stand up to peer scrutiny.
Anyway, their study of 3000 women concluded that a woman who has been raped once was seven times more likely to be raped again. 
I presume that this is partly because many rapes are carried out by intimate partners/former partners, while others will be perpetrated by someone in the victim's social circle which can leave them vulnerable to a repeat attack. I wonder if some may be explained by the victim's profile - e.g. a disadvantaged, vulnerable young woman would be much more at risk, and, dare-I-say-it, a black asylum-seeker.
I doubt we'll ever know the truth of what happened in that hotel room in this particular case, but I find it abhorrent that the fact that the 'maid' (sorry, dislike the name) has lied is given far more credence than the number of women who have come out publicly and said DSK has assaulted them to. I accept that one lie is legally recorded while the other is just media hearsay, but it just seems like character assassination to me. If that fact that you have lied on a previous occasion in your life means that nothing you say in court can be considered true, wouldn't that make most people unable to testify? Including incidentally DSK, who lied by firstly stating he had no contact with her. Shouldn't the two cancel each other out, and shouldn't the amount of other women who have made claims of sexual assault/harassment be allowed to be brought into the case if her previous sexual complaint history is allowed?
DSK could be innocent of this particular crime for all I know but it just seems to me that a vulnerable woman is having her past used against her in order to get him off, rather than the case being assessed on its own merits.