Martial arts is a broad and varied field. Although there are many no nonsense groups such as kickboxers, Muay Thai practitioners, and more, there exist groups such as Yellow Bamboo, a martial art that claims to harness "chi balls" and uses "white magic". Although completely bizarre in nature, these organizations are more common than one would think.
Does this exist in Taekwondo? With over 80 million practitioners worldwide, you bet. Although not common, stories like these can be found. The organized structure of Taekwondo makes it highly susceptible to quickly becoming a cult. Many religions across the world, from Christianity to Buddhism, incorporate their teachings into religious Taekwondo classes. There are thousands of Christian Taekwondo and Karate schools in America alone. Combined with the personality worship of many instructors, this can quickly become damaging to the mental and economic health of members. In certain subsets of the ITF Taekwondo organization, Choi Hong Hi, their founder, has his pictures displayed in tournaments. These pictures are shown large amounts of respect and bowed to. While some see this as merely a sign of respect, others have interpreted it as a cultish worship of an inanimate object.
A very interesting story is that of Tae Yun Kim, a Korean woman who came to America and claimed to have been taught "Tae Kwon Do with an emphasis on Ki Energy". She created "Jung SuWon" , a variation of Taekwondo. Her organization has been involved in several court cases, national investigation, and several shady or unknown deals. Her members have followed her around the country. Pictures taken inside her school show images of herself plastered all over the walls.
All aspiring martial artists should take a good look into whether or not their local school has the elements of a cult.