Just because a girl is wearing something sexy doesn't mean she's interested in you specifically flirting with her.
That said, getting mad when someone tries to flirt with you is overreacting, regardless of what you're wearing. However, sometimes it's the case that guys are disrespectful, or can't take no for an answer, so sometimes girls do get frustrated and need to take a harsher approach.
Some girls will wear certain clothing or try to attract certain attention from guys. But sometimes once they get that attention, they don't really know what to do with it, so they act in such a manner that is really confusing. That is what I have seen anyway. : )
See this is a tricky area. Now very woman has the right to dress how they want and girls wiho dress scantily clad are clearly seeking attention. They want men to feel orny when they see them, they are doing on purpose to create sexual tension. But that doesn't mean that they will flirt with every guy that cracks onto them. I agree that scantily dressed girls are a but far fetched and will be classed as "sluts" as they are seen to be more prone to have a sexual encounter than a girl who has just simply dressed to impress. Most guys will naturally think that a scatily clad dressed girl is looking for one thing. Although they do tend to show a little self respect, they still cannot be classed as a piece of meat that everyone has the right to crack onto.
So my opinion in general of scantily cald dressed girls are that they are just not right in the head!