They do make mistakes and often reduce their credibility by ending an investigation with a "mysterious" event that is supposed to placate those who still want to believe some paranormal activity happened. It's usually an audio recording that sounds something like "Mmmum mrprhphurph mummurmurph" which they claim sounds like someone saying "I am the god of hell fire" or something like that.
They utterly failed to see the painfully obvious CGI in nearly every frame of the "Glowing Gargoyle" video. If you step through the frames, the camera motion is causing lights in the background to leave long trails due to the show shutter speed yet the "gargoyle" is perfectly sharp in every one of them -- its bright glowing eyes are sharp as pins. It turned its head to the camera in a single frame leaving no motion blur proving it was an animation and the motion of it jumping off the playground castle was so unnatural that it had to be poor CGI. None of this was brought up even though in that very episode they had rejected a video because when they stepped through it, they saw a jump in motion which indicated CGI. Argh!
I think they just wanted a free trip to England.
Can you say Road trip! Sometime Fact or Faked has to choose the best videos they have whether they know it's faked from the start. This why the season is so short and long gaps bewteen seasons.