i think with feet as opposed to various other parts of the body, it's alot easier to be unconsciously revealing. Women not in the scene prolly don't wear flip flops to garner attention, they're just cooler, cheaper, and easier to put on whilst dashing out the door. I once asked a friend of a friend why she religiously got pedicures and wore flip flops. Her reasoning wasn't because she wanted special attention drawn to her feet, but simply because she always wanted her toenails to match her solar nails. Of course, because i'm twisted, i responded with "some men are turned on by pretty feet." to which she responded "eww! feet are so gross, who on earth would be attracted to something dirty like feet?" The next time i saw her she had slip on tennis shoes.
The point i'm trying to make is that you simply can't equate wearing sandals to wearing a low cut top and just say "she should have known better" chances are she didn't.