"She leaves a trail of horror behind her," he said, adding that she has a split personality that goes from angel to devil in a heartbeat.
"She just flips instantly," he said. "She goes from this incredibly sweet warm person to Satan."
The photographer, who feared retribution from McGee if his name were released, said he also knows Jesse James and would not be surprised if McGee and James had crossed paths.
He doesn't, however, believe that the two had a sexual affair, but admits he doesn't know James well enough to have an inside track. "He's a genuine guy," he said of the tattooed "Monster Garage" star who married Bullock in 2005.
He had less pleasant things to say about McGee, who dished to "In Touch" magazine on Wednesday that she and James had a twice-weekly sexual affair while Bullock was busy shooting "The Blind Side."
"She makes all her money from sexually-derived things," the photographer said. "I don't know if she's a prostitute, but she certainly flirts the edge."
McGee does work as a stripper, according to Radar Online, which reported she was booted from the Hustler Club and now works at Pure Platinum in San Diego.
McGee also provides sexy pay-per-view shows on SoCalGlamourGirls.com.
"I am the hottest busty tattoo and fetish model you will ever meet on a webcam," her profile says. "Come have a hot and steamy affair with inked girls like me on live video."
The photographer said her fetish work can be extreme, including squashing bugs and eating goldfish while naked -- and some things CBS will not publish.
"She has been making money off her fake boobs and being naked her whole life," said the shooter. "She knows the control she has over guys and uses it to the full extent."
McGee, who did not respond to email requests to comment, told In Touch that she never would have gotten involved with James if she knew he was still with Bullock.
"I would never have hooked up with him if I thought he was a married man. He gave me the impression they were separated," the tattoo model and mother of two told the magazine.
People reported that Bullock has left the house she shared with Jesse James. Bullock won the Oscar for Best Actress for her work in "Blind Side" shortly before the affair allegations broke. The couple has no children of their own but have been raising James' daughter from a previous marriage to ex-porn star Janine Lindemulder.