There are many teams who claim they are science-based and are searching for the "truth". If that is true, they will approach their investigations from a skeptical point of view, starting with testing the validity of the claims. If clients tell you a story associated with a particular location, then the first step is to find any information to back it up. For example, there was a case where we were told there had been a murder "many years ago" on a property we were investigating. Because I know local folklore often becomes distorted over time, I called the county historian for verification. Lo and behold, there really had been a murder there.
But many times, there is either no evidence of a certain claim, or there is information found that actually disproves it. One popular haunted location loves to lead their eager paying ghost hunters to a particular room and tell them that electric shock therapy was conducted on insane patients in there. Problem 1: that is the only building still standing and it never housed the insane, nor were any mentally ill housed on the entire property by the time it was built. It was a nursing home. Problem 2: at the time when the mentally ill were housed at the location (in another building that is long gone) there was no electricity. Kinda hard to conduct electric shock therapy without it. Problem 3: all the equipment bought and used at the facility is documented in country records. There is no equipment associated with such treatments.
Finding whether or not there is any basis in truth to a claim actually takes a little bit more time and effort than the "Show Up and Wait for Something to Happen Method" we commonly see in the paranormal community. Sometimes you won't receive a reply from historians and so you have to dig elsewhere. If it still isn't possible, then you have to throw the claim out. I know, it's disappointing that you can't base an investigation just on a creepy story. But it is irresponsible to feed into something that may be nothing more than a fabrication.
Some may argue that just because the historical facts aren't accurate doesn't mean a location isn't haunted. I agree. But the problem is that many times, people associate personal experiences (whether truly paranormal or not) with the history or earlier paranormal claims. We know from psychological studies that expectation and suggestion impact how we perceive things. For example, if there is a story of a Confederate soldier and someone sees a shadow out of the corner of their eye, they are already primed to "see" a Confederate soldier. If there is a claim of a screaming lady, and someone hears a high-pitched cry in the middle of the night, they will hear a woman's scream instead of a fox.
The ghost hunting teams aren't entirely to blame. Many times, the owners or managers of these locations use their hauntings as a source of income. To lure paying customers to investigate they either embellish existing claims or manufacture new ones. In some cases, they "borrow" claims from other locations. If one abandoned hospital has an infamous ghostly nurse profiled on TV, then claims of ghost nurses suddenly crop up in other places as well. In the location featured on the ghost hunting show I mentioned at the beginning, they seem to only allow teams who have been on TV to investigate - but not local teams who pay the taxes that keep the place open. To me, this suggests they are not at all interested in easing the minds of frightened employees or finding the "truth", they are looking for money.
Unfortunately, to some people in the paranormal community and the general public, the popular ghost hunting TV shows are the "golden standard" of paranormal investigating. But f they can't even get the history of the place they are investigating straight, how credible is any of their so-called evidence they present? And how credible are the teams who blindly emulate them?