Yes, there are such people who can "talk to the dead", but, unfortunately, a large amount of people who claim to be clairvoyants are not. There are people who claim to be able to speak to the dead who can't, but use their skills in finding out things when talking to the bereaved, and use that and some "intuition" and "guided guessing" to convince the bereaved that their loved one talks to them. As long as these folks don't charge too much money and it is comforting to the bereaved, I don't see much harm in it.
However, if any of these "clairvoyants" start asking for more money, as in saying they can remove a curse, or that the dead needs it given or sent somewhere, pull the plug on these con artists. These guys deserve jail.
There are clairvoyants in my family (they do tend to run in families) and whereas none of them have ever made money off the Gift, they can help friends and loved ones confronted by death, and do many other little services that aren't quite so dramatic.
