Kate Zabriskie, owner of Business Training Works, said using the phone for any reason while sitting on the toilet runs counter to the cause of cleanliness, NBC's "Today" show reported Friday.
"If you're in the stall touching the buttons on the phone, that's not good," Zabriskie said. "Those just aren't clean hands. And even if they're immaculate hands ... it's just not an image that I would think most people would want to project."
However, Zabriskie said convincing people to put their phones down at any time is a tall order.
"It's just almost become an appendage," she said.
Zabriskie said she hopes workers will at least make an attempt to hide their restroom phone use from colleagues.
"Use sense," she said. "If you are going to secretly shop in the bathroom, put your phone away before you walk out of the stall."