Some random thoughts:

I agree 100% that it is out of order to convene a 'meditation group' then turn it into a forum for a medium to channel some entity, whether real or bogus. Here are some issues:

1) It is common for many people to equate the spiritual with the psychic. (the two domains are different. Spiritual practice involves transcending the ego while staying grounded in ordinary conscious awareness. Psychic paths involve contact with paranormal reality, but this can happen when you're still egotistical--it just gives the ego more toys to play with.)

So if you want to attend a meditation event, and not be vulnerable to a 'bait and switch' find out if there is a contact number or e-mail and ask what format the meeting will follow. You can even say, 'I am happy to meditate, but I am NOT iterested in being indoctrinated or in listening to someone channelling psychic entities.' That way, if you know what the format will be like, attend the meeting, and they pull a bait and switch, you can stand right up and say 'You did not tell me the full truth and this is deceitful and a waste of my time.' IT also warns the other people present that they are in a bad situation. If there is no contact number for the group, at least know its at your own risk.

2) Psychics who are immature/badly trained are tempted to develop their powers and ignore basic life skills like how to earn an honest living, and often neglect learning to conduct adult relationships in an ordinary, human manner based on honest communication. It can be tempting for psychics to get hooked on earning their living as paranormal superstars and con people into supporting them on that basis. If you read The Buddha From Brooklyn by Martha Sherrill, you get a story of a woman who started as a psychic channeller with good intentions. She ended up running a Tibetan Buddhist cult.

Persons with genuine psychic powers and who are responsible in their use are rare. And they do not advertise. Those powers are a burden and a heavy responsibility, not for fun.

Personally, I believe in prophecy as I've experienced it personally and have been in touch with people who knew things about me that they couldn't have possibly known otherwise, like when my father called up and told me not to spoil his dog Princess (the posting is elsewhere).
But the belief in being able to contact "entities" is sort of strange to me. Are these entities angels, demons or what. And how could you verify that they exist?
I even ran into a site that teaches you how to be a psychic using fraudulent techniques.