"There's a sucker born every minute" -- a phrase often credited to P. T. Barnum (1810–1891), American showmanShould you believe a person who tells you that the moon landings were faked on a Hollywood production lot? Why or why not?
Can you trust anyone who tells you he talks with the dead? Why or why not?
Honesty and truth are not necessarily connected. Honest people may promote falsehoods, believing them to be true. Dishonest people may, on many an occasion, tell truths -- for various reasons, usually because they have no stake in it. Involved are two different dimensions of judgment, intention vs. facticity.
These are not particularly deep issues; but some careful thought may be needed to sort out those people we can trust or not, from the reliability of the information we get from them.
A whole lot depends on what they present as evidence. How might you evaluate it?
To continue the discussion, see Can John Edward Talk to the Dead? Assessing Evidential Burdens..