I don't think doing porn makes somebody "bad". But making porn can have a toll on people, you might feel forced to do things you don't want to do, you might feel ashamed after doing it, you might feel uneasy when people recognize you in the street... well, it's quite possible you might wish you never did it.She hasn't really turned it around though. She's just gotten more successful at exploiting her notoriety.
Which I think is kind of key here; doing porn doesn't make a person "bad", but it does undeniably make them notorious. Its a short-cut to fame, and like all short-cuts it has its price - especially in the public consciousness.
What I kinda dislike, is when this script gets flipped and in order to gain currency the person acts like the thing that made them famous was "bad", and that they were victimized by it.
Mia Khalifa is making a good living out of the fame she got doing porn, but even she being the 1 in 1,000,000 most succesful actress in the industry, she is partially remorseful and thinks a lot on what her life would have been if she hadn't gotten in the industry.
So I don't think people who do porn are bad, but that porn can hurt people and teenagers shouldn't do it casually. It might have unwanted repercusions on the rest of their life.