In general, if the "healer" is not a true tzaddik ("righteous one"), such as a Rebbe, the healing is always a mixture of good and evil. It is certainly possible for a person's soul to possess psychic powers. However, with the exception of a very few true tzaddikim, psychic powers are a mixture of light and darkness, at best. Often, they are completely negative. When good and bad or truth and falsehood are mixed together, the final result is usually negative. Thus if there is a mixture of good and evil, it is better to stay clear of these practices.
There were great tzaddikim, such as the Rebbe of Kamarno, that possessed psychic powers. They related that when they arrived at a certain maturity of understanding, through being involved in the truth of the Torah and Kabbalah, they understood that these psychic powers were detrimental to their own progress in the true service of God. Even though these powers were purely good, they asked God to remove them as they felt that these powers were not helping them or the world in the true service of God. They desired to serve God purely through the study and teaching of the Torah and the performance of mitzvot.
