What personality traits does sexy and revealing clothing correlate with? Is there some unifying characteristic that distinguishes women who wear form-fitting, lowcut, see-through and other kinds of revealing outfits?

Are they more extroverted, do they rate higher in (sexual) sensation seeking, do they have high or low confidence etc.?

Is there any research on this?
This question is primarily about Feminine psychology. Men identify less with their clothing than women and are stereotyped as promoting self-objectification many times. 

In American society clothing norms are for women are very complex and are difficult to navigate. Because sexuality is indeed related to which parts of your body you do or do not reveal there is direct clinical quality relationships between certain clothes and states of mind. However generalizations made about a persons state of mind based on their clothing can often be faulty. People experience stimuli in their lives which prompt individual responses that do not match their overall personality.

Active research along these lines has been published. In Enclothed cognition it is reported that a lab coat is able to change the perception and increase attention when associated with a doctor. Likewise in More Than a Body: Mind Perception and the Nature of Objectification studies were done comparing the agency viewed by people on clothed, naked and sexualized pictures. In conclusion they said:


  Whatever the positive or negative effects of focusing on someone’s body, its effect on mind perception seems clear. Those perceived in terms of their physical characteristics are not completely stripped of mind but are, instead, seen to possess a different kind of mind, one lacking in self-control and moral responsibility but relatively more capable of pain, pleasure, and emotion.


In "You Are What You Wear: What Your Clothes Reveal About You" shopping for clothes is treated as a therapy to correct negative schemas. Though its validity has not been proven it seems rational.

To directly answer your questions about "Are they more extroverted, do they rate higher in (sexual) sensation seeking, do they have high or low confidence etc.?" according to You Are What You Wear it largely depends on age and the norms for that age. A college age girl in a revealing dress would have a different state of mind than an older woman in a similarly revealing dress.