I will raise a caveat here :
"For the present, we tell you that there are spirits who delight in such personation, and who have the power, under certain conditions, of carrying out elaborate deception. Such take names which they see to be desired, and would reply equally to any name given them. "
"It remains to speak of the agency of a class of spirits who, from mischievous design, or from pure sportive fun, or from love of mystification, frequent circles, counterfeit manifestations, assume names, and give erroneous or misleading information. Such are not evil, but unbalanced spirits who lack even balance, and who delight in plaguing mediums and circles: in giving exaggerated tone to communications, in introducing false elements, or in personating friends, and reading in the thought the answer which they give to a query. The work of such is that which causes you to say that spiritual manifestations are frequently foolish or silly. This is due to the efforts of these spirits, who, from fun or mischief, counterfeit our work, and play on the feelings of those who trust them. These are they who personate relatives whose presence is desired, and answer to their names. These are they who make true identification of friends in mixed circles impossible. Most of the stories current of such return of friends are due to the work of these spirits. These are they who infuse the comic or foolish element into communications. They have no true moral consciousness, and will pray readily, if asked, or will do anything for frolic or mischief. They have no aspiration beyond the present: no desire to injure, but only to amuse themselves."
"They are usually shrewd and clever at such work, and they delight in presenting bewildering phenomena for the purpose of disturbing the mind. They victimise mediums in divers ways, and find a pleasure in the bewilderment of mind which they cause."
"They are able to psychologise a mind over which they have gained influence....These, again, are spirits who befool inquirers who have asked for personal information. They return plausible answers, and bewilder the deluded inquirers, or if a personal friend have once appeared, and given a good test, his or her place on the next occasion may be filled by one of these spirits, who takes the name and replies to queries, giving vague and unsatisfactory replies, or telling false stories. It is always well to put the personal element as far from you as possible, lest you open the way to deceit."
"We deprecate always any unlicensed meddling."
"Doubtless it is perilous for such to meddle, more especially if their interest be only in the marvellous, to gratify an idle curiosity, or to solace their own vanity. "
The above is from
Spirit Teachings, by William Stainton Moses, which I would suggest as a 'must read' for anyone interested in spirit communication.
You can read it online
here, but it's easier to download it.
The PDF is
here, the MS Word version
here, and the plain text version (zipped) is
here.
I downloaded the MS Word and converted it to a .mht file, can then view it in a browser easily.
Be advised it is a very long, but incredible read.