I had an interesting conversation with a gentleman who is part of a fairly well known location that is a hub for paranormal investigators and ghost hunters during a speaking engagement at a library in Grafton, Ohio this October. We were discussing plans on my group possibly coming out to the location to investigate particular aspects of the environment (humidity and other factors) during the colder months of the year when the conversation shifted toward something that I had often thought of; are ghost hunting and paranormal investigation groups ruining the famous places they like to investigate? No, not by running around in the dark screaming or by vandalizing, but by just being there.
Granted, this should not be left to investigating Civil War sites, but could also be applied to abandoned hospitals or prisons as well as the house down the street that has a ghost or is haunted. Is it possible that the constant influx of thrill seekers at historical sites will ruin it for future investigators? Who knows for sure, but it seems logical that continous emotional imprints can not be conducive for obtaining good evidence of haunting phenomena at historical locations.
So, what methods are getting the best results? Have particular locations noticed a change in the type of evidence gathered? I have not been able to find an answer as of yet, but hopefully as the amateur paranormal investigation movement evolves people will move away from behind the safety and security of their tools and realize the potential of communication on the interaction level beyond what is normally used.
As far as ruining sites for future investigators I feel it is a legitimate concern. The high intensity of emotions that accompany an investigation that are repeated over and over are bad enough. If you then realize that there is potential for some investigators to affect the environment by their beliefs and possibly leaving psychokinetic "residue" attached to the environment for future investigators to read with their instruments. As many stumble around in the dark in search of their proof there are many of us also who are in search of answers surrounding the effect of our culture on the paranormal itself.