I think most people aren't prepared for the subtlety of clairvoyance. Just as an experienced sailor can tell a storm is coming from the peculiar scent of a breeze or a computer nerd can tell that one particular part of a batch of code is going to help or wreck an operating system, a good clairvoyant has to process a million subtle details, often all at once, often by instinct, to figure out who is there and who is trying to communicate, and who is pretending to be another entity (trickery). Trickery is why seances and Ouija boards should be avoided. Spiritualists often think they are talking to somebody's dead grandma or Marie Antoinette and that is only true a small portion the time. Typically they're talking to an impersonator. There are plenty of entities who hate humans, many who love them, and a vast quantity who are completely indifferent.