I think that the three types of gurus that the Dutch theologist Dr. Reender Kranenborg distinguishes are useful. Kranenborg specializes in Hinduism and new religious movements at the Free University in Amsterdam but I think he retired this year.

1. the spiritual advisor for higher caste Hindus who also performs traditional rituals and who is not connected to a temple (thus not a priest).
2. the enlightened master who derives his authority from his experience, such as achieving moksha. This type of guru asks for unquestioning obedience and can have Western followers and even Westerners have become one, for example Andrew Cohen.
3. the avatar, a guru who claims to be an incarnation of God, or to be God-like, or an instrument of God, for example Sathya Sai Baba and gurus from the Sant Mat lineage.

I estimated the chance that there is something as a healthy guru disciple relationship as follows
1. "the spiritual advisor" 70% chance that this can be a healthy relationship if this is based on a training by a guru with a lineage and some objective exam or test. (in other words I do believe because >50%)
2. "the enlightened master" 30% (I do not believe because <50%)
3. "the avatar" SSB and to a lesser extent Rawat who also has something of type 2, 10% (I do not believe because <50%)

Oh, and I stay here as long as I like until the moderators kick me out. It may take a year or something before I get bored here because I continue to be interested in the subject of cults and gurus.