A worrying amount of sexual assault victims have been asked this question, which is completely and utterly wrong. There is no debate to be had here, no argument to support it, no analogy to justify its inherent immorality: "don't leave your house unlocked if you don't want to be burgled" for one. It is never, and can never, be the victim's fault.
It is for that very reason that asking the question: "what were you wearing" is wrong. It directly implies that they were in part responsible for what happened. Each time a victim gets asked this question, they may start questioning themselves, feeling guilty, possibly even ashamed. Equally, some victims may be hesitant to go to the police for this reason; let's say it was Halloween and they'd been rocking a sexy and cute bunny corset with fishnets and someone had taken advantage of them, they may feel that the police will blame them and not bother either helping or listening. Therefore, this question has to stop being asked. Anyone can wear anything, without be judged and most certainly without being blamed for an assault.
Whilst your clothing may intentionally or unintentionally attract onlookers, that does not in any way, shape or form allow them to take advantage of you. Your body is yours so if you want to flaunt it, go for it, and if you want to go down the vintage, baggy look, then you're much cooler than me! Whatever you want to wear, wear it. Sexual assault is on the perpetrator, not the victim;
It. is. not. your. fault.