Gee, I wonder why. Because perhaps most if not 90% of the retail stores provide clothing solely designed to make every woman look like a slut to enhance her love appeal even when it is totally unnecessary for their age. Media broadcasts women in slutty and loveually appealing roles (aka that Megan Fox thread on the forums went from a simple scandal to how hot she is in 5 replies) When it's all that you see all around you, it's rather difficult to go against the norm.
I based it on the excessive cleavage, oversized hoop earings, and pink lipstick. Around where I live, it's certainly not the norm. It's only the norm with, well you guessed it, sluts.
Edit: I never stated she was a slut, and while your point may be valid, she is still dressed like a slut. Whether it's the norm or not.