The devil is a liar and the father of lies.

Remember the film Emily Rose?  A companion book purported to be the 'real' transcripts of the conversations between the demon, the victim, and the exorcist were made available through a couple of Catholic booksellers.  Supposedly the demon was forced to admit things - like communion in the hand was evil, and other stuff.  Throughout the centuries devils were supposed to have been forced to say all sorts of things.*  Were they true?  Maybe - but truth mixed with lies is never something to put faith in...  I found the following on Dr. Edward Peters blog, In the Light of the Law:
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Exorcists telling their stories...
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Finally, it is very important not to believe or disclose any comments made by the devil/possessed during the rites. Falsehoods are bad, but falsehoods mixed with truths can be devastating. No matter how many truths about oneself or about others that one might hear during the rites, one should not assume that any other comments are, or even might be, true. Nothing disclosed or even intimated by the possessed can be trusted. Absolutely nothing.
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Heresy is just like that.  Intercessors and mystics, beware of playing the prophet.
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Just sayin'.
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*Yes, Christ forced devils to identify themselves and so on, and a priest acting in persona Christi and authorized to perform the exorcism can do likewise - but the results or transcripts should not be broadcast, lest the faithful be confused or scandalized.