So, my daughter got my wife one of these for Christmas, because my wife likes to watch Ghost Hunter shows.
http://ghostmeter.net/It's an EMF meter. Yes, we went all around our house and didn't find anything conclusive, but our house was almost totally rebuilt a few years ago so there's little time for any new ghosts to settle in.
However, what did set it off were clock radios, electrical wires in the walls, the fridge, the electrical panel, and most definitely every audio component in my system. EMF generators for sure!
So if you are wondering why those Alan Mayer quarts crystals seem to work it's because your system is throwing off all sorts of EMF radiation and they are doing something to cleanse that gunk.
Maybe we should all build a Faraday cage around our system racks!
Bob