Is there any evidence for the reliability of these devices? Like putting an EMF reader in a sealed box that protects it and checking if it goes off on its own at random intervals?
I had been thinking that a reliable experiment to prove if ghosts exist (and if the readers work) would be to "contact" some known spirit and ask them some 100ish yes/no questions they should be able to answer by setting a couple of readers off and if they get something like 90% or more right then the matter would be settled.