Is it the crazy sized boobs? That is the biggest negative that everyone (including me) has. I also have a slight issue with the dark hair, but at least in their morning illusion form, the colored hair looks nice.
The issue isn't so much the boob size as it is the shape. Alot of bad artists just make huge circles and it really doesn't work. Big boobs need to be drawn/modeled carefully and the further beyond normal sizes you go the harder it is to keep them looking good instead of just rediculous which is what happened here.
The tramp stamps are another issue honestly it's one thing if they got covered in some kind of strange pattern as the magic corrupts them that'd be fine but the tattoo's in this game scream "cheap hooker" which is a major turnoff. The original uncorrupted girls just flat out look better to me, the proportions are much more enticing than absurd tier giga tiddies and blimp scale arses.
If i had to make a recommendation to the Dev i'd say stick with the original uncorrupted models but have them just turn pale and give them more tribal/magical looking tats. Maybe have one or two who go giga tiddies to cater to the "bigger is better" crowd but have it be a slower more gradual thing.
Above all the biggest thing to me is the fact the current vampire girls all have the same body shape, little to no variation makes things kinda dull which again is why the uncorrupted models are better in my opinion since they do have greater variety.