The main reason Shark Tank star Barbara Corcoran fires people? Having a bad attitude . On a recent podcast episode of The Burnouts, Corcoran shared that after hiring her first salesperson from another firm and training her “like crazy for a year-and-a-half,” there was one thing training couldn’t fix: her attitude. That experience taught her a straightforward, non-negotiable hiring principle. While skills can be taught, a good attitude cannot.  “I learned a very valuable lesson: [if you] have somebody who has a bad attitude, they’re going to suck up other people into their attitude,” Corcoran said in the podcast episode.  One person’s negative outlook can bleed into the rest of the workplace. To protect her team’s culture, Corcoran said she fires people with a bad attitude “right away,” because she doesn’t want them to “contaminate” other employees’ mindsets. “I want a happy atmosphere,” she added. “The minute I see a complainer, I make an appointment to fire them.” Corcoran has been vocal about how negative attitudes impact workplace culture in the past. When asked why she was so irked by complainers in a past episode of Diary of a CEO , Corcoran answered that complainers are “thieves.” “They take your money away and they take your energy, and the most valuable asset you have is your energy,” she said in the episode. “And if they take your energy away, you’re not going to deliver enough to everybody else—there’s not enough to go around.” When it comes to how and when she does the firing, she said, “always on a Friday.” Corcoran received social media backlash for this practice in the past, but it seems like that hasn’t changed her day-of-the-week preference.  Corcoran’s firing script is short and simple, too. “I say, ‘it’s not working out, you don’t fit in here,’” Corcoran explained. “And I give no more information than that. […] The first time I fired someone, I tried to explain to them what was lacking, and you never win the argument. You’re better off saying, ‘you just don’t fit in here.’” While she never argues the case, Corcoran isn’t necessarily operating from a place of cruelty or impatience. She said she always points people in a different, forward direction. “I would tell them where they would fit in, what kind of job would make them very, very successful, which I really believed,” she added. “My partner used to say, when I fired someone, they walked out like they got a promotion.” It’s clear that Corcoran believes that workplace culture has to be actively maintained and protected—and that she’s willing to be the one to do just that.