Yes, "cult" in itself is a somewhat ambiguous term. Because of this, one must define what they're talking about when they use the word. Some use it to describe what they consider to be heresy. Others strictly apply it in a secular sense, to describe "a group that deliberately uses deception, manipulation and psychological abuse to control the thoughts and actions of its members as opposed to a group that acts morally and ethically." Yet the use of such a definition demands clarification of the terms "morally and ethically". Here's an interesting site which attempts to do just that:
http://www.csp.org/development/code.html
Here's a quote:
In any community, there are some who feel called to assist others along spiritual paths, and who are known as ministers, rabbis, pastors, curanderas, shamans, priests, or other titles. We call such people 'guides': those experienced in some practice, familiar with the terrain, and who act to facilitate the spiritual practices of others. A guide need not claim exclusive or definitive knowledge of the terrain.
Spiritual practices, and especially primary religious practices, carry risks. Therefore, when an individual chooses to practice with the assistance of a guide, both take on special responsibilities. The Council on Spiritual Practices proposes the following Code of Ethics for those who serve as spiritual guides.
Then it goes into 9 ethics guidelines for those who take on a role as a "spiritual guide".