The ad spawned numerous parodies, such as one from Saturday Night Live and this one below from Elvira.
Generally, being a witch entail gaining power, but encountering some sort of social friction as a cost (though there are exceptions, and I'll go into them later.) Witches are often portrayed as villains in fairy tales, usually as out of control women who want to disrupt the status quo. This makes sense, since historically, persecution of witches has been tied to social fears of independent, freethinking women.
Most of the transformations and spells that witches offer to others tend to involve this trade off as well. The story Side Effects entails a witch who will grant transformation wishes but at the price of a negative transformation in the mix. And there's a growing sub-genre of witch-themed gender change stories, like The Witching Brew, where an exciting seduction is played off against the risk of losing one's manhood.
The idea of witches "paying a price for power" is illustrated in Madoka Magica, which is a fantastic anime I've just finished watching and that I'll be reviewing in more detail later on.
Harry Potter, Sabrina the Teenage Witch, Charmed, and other TV shows and movies have recast the witches (or at least, some of them) as the heroes. I predict that a few factors will make this trend continue and grow in the near future. First, our conception of gender have shifted, and strong women are more likely to intrigue us than horrify us. Even in movies where the Witch is still the villain, such as Snow White and the Huntress, the princess is recast from a slumbering, passive character to a warrior leading an army. Second, a decline in religiosity among young people will probably prompt more interest in the aesthetics of concepts which have been traditionally feared by religion, like witchcraft. Third, "dark" stories exploring complex nature of the hero have become increasingly popular, and the occult represents a great setting for that.
What is your favorite witch-themed transformation story? Leave a link in the comments along with your reason why you like it.