I have never heard of a successful conversion therapy.  I have, however, heard horror stories from people who were subjected to it.  Patients are often shamed and humiliated, told they are bad and horrible people, and told they choose their sexuality.   They are told they are unnatural.  Many of these "therapy sessions" have religious overtones where the patients are told they are going to hell for being bad.   The practice of modern medicine should not include outdated, midieval torture sessions to try to force patients to conform to another person's standards.  Gay people are productive members of society and merely being gay does not predict whether or not they will be a good or bad influence on others, whether or not they will be successful, or whether they will go to hell. This is a practice that merely helps parents feel better about their own selves, to let them say they have done what they can to prevent their child from being gay.  The practice does not help the patient, and only does harm.  It needs to be banned.