It's funny that your description of Vanessa also applies to Nika as well. I wonder if Nika will ever have a "we're not so different" moment with Vanessa?The first impression which Vanessa gives is that of a haughty, dishonest, egocentric person, so it’s natural that some people dislike her.
She tested Nika when she stripped in front of him to see what he’s made of, if he’s yet another “inferior male” as she says, an underhanded tactic on her part but it was her own way of getting to know him, she’s just built different.
Even if she likes messing with people I don’t think she’s a horrible person, rather someone who sees the world as a dangerous place and has learned to adapt and even gain some pleasure from it in a fucked up way. Once she warms up to Nika and his family and learns that they’re not potential enemies and she can trust them she’ll prove herself a smart, valuable ally in the chessboard of Wollust.
I was just thinking about the "dislike her" part of your statement, and it occurred to me... how many people at college would like or interact with Nika if Nami wasn't there by his side? How many times has Nami been there to not only keep Nika's worst impulses under control, but to guide Nika's interactions with others and balance out is anti-social behavior.