1. Mistaking Allegiance to the Guide, Books, or Practices as the end goal of spiritual growth/enlightenment, rather than using them as 'tools' to reach God.
2. Undergoing humiliating practices as a method for 'ego-destruction'. The Ego should fall away naturally over time. The attempt to hasten its departure too abruptly can lead to self-hatred and shame rather than relief.
3. Cutting off contact with 'the outside world'. While periods of isolation/retreat can be extremely useful for calming and intensifying the mind, in a cultic contact it can build a dependence on an 'in-group'. A spiritual practice should also have the goal of lessening suffering in 'the world' whenever possible.
MISTAKING A CHANGE OF COSTUME FOR INNER CHANGE
It's typical of cults to place a good deal of emphasis in changing names, costumes, dietary habits, etc. To build a 'separate world' even within lives led within the mainstream culture.
In the beginning, perhaps in the days and weeks after 'initiation,' a seeker is likely to believe the apparenent changes are part of a major interior, spiritual change.
In a cult there is typically little emphasis put on 'working thru' one's past. It is often suggested that the past doesn't matter, since one has already 'transcended' the earlier, troublesome identity.
In this respect, the Cult is like a Drug. It gives the illusion of transcending one's pain or guilty past. Yet, ironically, it prevents skillfully approaching and lovingly releasing a painful past thru compassion, mindfulness, and forgiveness.