Wicca is a religion based on trust. In fact, that's a key saying: "Perfect love and perfect trust." So what about those people who take advantage of others, using magic as a way to get money, power, or sex?

Well, they're scum.

Never allow a teacher or mentor to make you do something you don't feel comfortable with--and never, never trade sex for teaching. People who are out to exploit you will make many extravagant claims. Listen patiently, nod, then tell them to fuck off. If they won't teach you without getting laid, they're not qualified to be teachers.

Some legitimate teachers do charge, but their fees tend to be just high enough to allow them to eat. If someone is asking you an exhorbitant price for a course that is "guaranteed to make you an expert in All Things Magical!", the only appropritate response is, "Bullshit."

Some people get their kicks out of dominating others. These are the people that run cults. Refer to the Isaac Bonewits Cult Evaluation Frame.

A word on vampires: my opinion is that they do not belong in Wicca. It doesn't mean you can't like vampires, simply that vampires of any kind--psychic, emotional, or physical--should stay outside the circle.