I wouldn't exactly call it "corruption". To me, corruption means losing sight of what's important due to hedonism, ego and lust. You could argue that Felicia is the most corrupted character in the game before she even enters the Club . She abandoned her hopes and dreams to become her husband's shiny toy because her ego and hedonistic lifestyle she adopted in college couldn't bear living in a small town. Despite having all luxuries in her life, she can't even financially help out the school without her husband's permission. She has to resort to most extreme measures to get back at her husband, because she'd be nothing without him. She's not really a person anymore, because she sold her soul a long time ago and it's too late to get it back. So I guess no matter what she does, she's not Felicia Ford, she's just Elias' shiny trophy.
Compare that to Vicky, who experienced much worse things than Felicia, and came out on top in the end. Yes, she's a nasty slut that did uspeakable things on camera for years, but her love for Edwin never faded. She was still a good mother to him, and they have a good relationship to this day. She never let her "career" get in between her and her son. I wouldn't call it corruption if she came out of it the same person. It takes a lot of character to not succumb to the pitfalls of the porno lifestyle, especially for women. No matter how much Vicky enjoyed getting railed, it was still a degrading and nasty experience, and she got out intact. With Edwin seeing her clips, she might have unwittingly created a monster, however. I would say Edwin is already pretty corrupted, even at the start of the game.
The same goes for Rose. I would say she's pretty "uncorruptible", unless she abandons her daughter somehow. She was dealt a bad hand, and she's doing everything in her power to save her family. As for her manipulating Edwin, he deserves everything he gets for working in such a place. None of the club employees have much of a moral high ground. Edwin and Ian had a choice, Rose didn't.
Veroinca is 50/50. I'd say she's pretty corrupted by her ego, as going so far as to join the Club is a pretty bad decision. It's obvious her ego and pride have impaired her decision making. On the other hand, it's admirable to fight for your dream and livelihood like that. The logical decision would be to cut your losses and move on, but when you put your blood, sweat and tears into something, it's pretty hard to let go. She's still fighting for her dream, and that's pretty badass.