Bullying is one of the most obvious signs of a toxic workplace — and it's lot more common than most would expect. 

That's according to Robert Sutton, professor of management science at the Stanford University School of Engineering and author of "The Asshole Survival Guide," and "Good Boss, Bad Boss." 

Nearly one out of every five US workers has experienced or is currently experiencing workplace bullying, according to a 2017 survey of more than 1,000 Americans by the Workplace Bullying Institute, an education and research organization on office abuse. 

But what are the other, more subtle indicators your workplace is awash in unfair practices and bad, unproductive, and perhaps even dangerous behavior? Here's what the experts said.

1. People at work don't speak up. 

One of the telltale signs that an office is toxic is how much, or how little, people talk in meetings and in group settings, Sutton said. 

"When people with less power try to speak up, they get shut down," he told Business Insider. "There's sort of a cold silence as leaders talk. That, to me, is a sign of fear." 

When you've got a few people in power who do all the talking, and everyone else sits idly by, it's an indication that not everyone's ideas are heard, and that there are stark differences in the way people at different levels are treated, he said.

2. Your coworkers lack energy. 

"People being worn out, that's a sign of a toxic workplace," Sutton said, who explained that lethargic coworkers could indicate neglect, employees being overworked, or that they have started thinking that contributing isn't worth the criticism they'll likely receive. 

3. Employees don't stay at their jobs for very long. 

If you catch wind that a company has a high turnover rate, run the other way, Sutton said.

"That's clear as day, when people start leaving," he said. 

4. People criticize one another and there's a lot of gossiping. 

In a toxic workplace, communication isn't clear and open, which leads to misunderstandings and arguments, according to Paul White, a speaker, trainer, psychologist, and co-author of "Rising Above a Toxic Workplace." Leaders don't express appreciation and praise, and that negative attitude spreads throughout the company.

"Grumbling and complaining by employees is common — they can find something to complain about almost anytime. Then sarcasm and cynicism show up, which demonstrates a growing lack of trust of management and leadership, and turns into a low level seething disgruntlement," White previously wrote on Business Insider.