I think people who believe that cemeteries are filled with ghosts and parasitic entities are harkening back to old wives tales. I have always enjoyed walking through old graveyards and have never had a problem or a run in with any evil or negative spirits.

I even took a Ouija Board to a graveyard that was supposed to be very haunted once.. I sat there alone for nearly two hours in the darkness trying to make some kind of contact.... and nothing happened.

I think your safe to experiment with EVPs in a cemetery.