My wife and I are amateur paranormal investigators, and Ghost Hunters used to be one of our favorite shows on all of television... BUT, we started to see a trend in them either fabricating evidence, or flat out making something out of nothing, starting a few seasons back. Because of that, even tho I do think they've caught some pretty good evidence, in my eyes it all has to be thrown out because we just don't know what's legit and what isn't. Even their former cast member, Donna Lacroix, came out last November and admitted she caught them (either the producers or the investigators) fabricating evidence. So yea, the show has lost all credibility with us, but we'll still watch it for shits and giggles every now & then. As far as entertainment value, I like Ghost Adventures more than Ghost Hunters, but again, I can't take it too seriously because they've been caught faking too.
It's the same thing with pretty much all the paranormal shows on TV... they've either been caught red handed faking shit, or they're trying too hard to say that every noise & shadow is a ghost... or a little of both. Paranormal State, Most Haunted, and Psychic Kids are the worst offenders for faking evidence...
As any paranormal investigator can tell you, most of the time no matter where you're investigating, you're not going to catch much good evidence in one night of investigation. I'm lucky to get one EVP per investigation, and as far as video evidence, that's even harder to get something substantial.. but it makes it that much more satisfying when we do get something good.
It comes down to, they need ratings and constant episodes where all they catch is one EVP or nothing at all, are NOT going to bring in ratings... so, what are they going to do? They're going to do what they need to do to keep the show on the air.