“trifield (emf) meters are a very legitimate item which can be used in any scientific setting as easily as on a ghost hunting expedition. the question is whether the meter measures paranormal activity and the answer to that is not helped along by the misuse of these meters by nearly all of the tv ghost hunting groups. my meter (one which measures 'natural' fields) will detect lightning long before i hear the associated thunder or seen the flash. but whether that same meter will detect ufo activity is yet to be determined.
and i agree with @hrh mortimer--if you're going to ban cleansings and blessings and spells and spirit-embued items, let's ban bibles and crosses and prayers and stars of david as well--there's not a jot or a tittle of difference.