If I see a girl running around the bars with a very short skirt, high heals, etc. essentially this.
Honestly I don't see a problem with it, I've never called a woman a slut for dressing up like this for Halloween. Usually the (now ex) girlfriend would be the one calling them sluts.
All I'm saying is, if you dress like this expect to be whistled, wooted at, and other woman to call you a slut (mostly because they are jealous)