My character called her a prostitute because he mingles with lowlives, drunkards, that sort of stuff. Meaning realistically he'd see prostitutes often. Prostitutes showing shoulders/ankles at the time, that is what he perceives as the prostitute standard. It's something that people don't normally bring up when people are in a Medieval setting, seeing as it is a social standard of that time. Since we belong in a time where that social standard is redundant and obsolete, it's sort-of a fact that we just kind of ignore.
My other character, Scardrac, who is pompous and arrogant, simply knows the prostitute standard because he's seen so many women showing things that he just knows in the first place. And decides to be misogynistic and correct them anyways.
Again, back onto the point of the whole getup thing and how people may perceive it. Like I said, not everyone knows the fact, and I realize that we're not complete copy/paste medieval, but some people try to be that. I don't think any side of the question should be prejudiced against their standpoint. However, I don't like being shut down and told "Nobody cares as much as you do" because I was trying to share some history. I apologized to the person, making sure they knew what I was trying to do, and that it was nothing personal.