You are right to be very skeptical:
This section contains a list of Certified Mediums who have completed the Mediumship Mentorship Program facilitated by Doreen Virtue.
See what Deuteronomy 18:10-12 says about mediums. The Catholic Church has a document on "New Age" that talks about exactly this phenomenon:
2.2. What does the New Age claim to offer?
2.2.1. Enchantment: There Must be an Angel
One of the most common elements in New Age “spirituality” is a fascination with extraordinary manifestations, and in particular with paranormal entities. People recognised as “mediums” claim that their personality is taken over by another entity during trances in a New Age phenomenon known as “channeling”, during which the medium may lose control over his or her body and faculties. Some people who have witnessed these events would willingly acknowledge that the manifestations are indeed spiritual, but are not from God, despite the language of love and light which is almost always used.... It is probably more correct to refer to this as a contemporary form of spiritualism, rather than spirituality in a strict sense. Other friends and counsellors from the spirit world are angels (which have become the centre of a new industry of books and paintings). Those who refer to angels in the New Age do so in an unsystematic way; in fact, distinctions in this area are sometimes described as unhelpful if they are too precise, since “there are many levels of guides, entities, energies, and beings in every octave of the universe... They are all there to pick and choose from in relation to your own attraction/repulsion mechanisms”.(22) These spiritual entities are often invoked 'non-religiously' to help in relaxation aimed at better decision-making and control of one's life and career. Fusion with some spirits who teach through particular people is another New Age experience claimed by people who refer to themselves as 'mystics'. Some nature spirits are described as powerful energies existing in the natural world and also on the “inner planes”: i.e. those which are accessible by the use of rituals, drugs and other techniques for reaching altered states of consciousness. It is clear that, in theory at least, the New Age often recognizes no spiritual authority higher than personal inner experience.
I'd guess that other churches would have a similar view. If you're interested, you can read through more of the document or have a look at the table of contents (see the list of Resources and the General bibliography).
Of course, Doreen gives all credit to God and the angels.
"Of course". I wonder where all the money goes.