Stormy Daniels is getting trashed by Donald Trump's attorneys for claiming, under oath, she sees dead people, but a veteran ghost hunter says they're barking up the wrong haunted tree ... 'cause he's seen her skills, firsthand.

Here's the deal ... one of the porn star's side hustles is as a paranormal investigator, which came up in court last week as team Trump tried to use it to mock her and discredit her testimony.

David Childers has been in the paranormal field for nearly 30 years, and had a much different take as he watched the trial play out, because he's gone ghost hunting with Stormy on her show, "Spooky Babes" ... and he tells TMZ she's the real deal!

Childers swears to Zuul he's observed SD, on several occasions, know scarily specific details about dead people and spooky places -- with no prior information -- and, for him, that's documented proof of her abilities.

He says spirits flock to Stormy because she is a "100% good person" ... but, interestingly, he adds they can't have her back. As TMZ previously reported, Stormy wore a bulletproof vest while testifying in the Trump case due to safety concerns.

We know what some of you are thinking, and Childers says ghosts simply can't protect the living -- despite the Hollywood heroics of folks like Patrick Swayze.