Ok, I think I have to clarify something.
Charlotte as a character is a whore (I think bitch is a better word?) because she dresses and acts like that, knowing that she can obtain what she want in that way.
It's not like the designers made her like that just because fanservice (well, they obviously did it for fanservice), at least they tried to make an excuse to "justify" her.
At least that's what I think, in the end it can be a bit hypocritical, so... ¯\ _ (ツ)_/¯
Either way I don't like Charlotte for her design and personality.