Barbara Corcoran is a tough hiring manager. The real estate mogul and Shark Tank investor ruthlessly weeds out complainers during the hiring process. In building her business, Corcoran quickly learned to prioritize hiring for happiness. Negative people drag down the morale and productivity of everyone around them.

Corcoran also takes a candidate's professionalism seriously. When you walk into her office for an interview, she's carefully analyzing everything -- especially what you wear.

Making a good first impressions

On a recent episode of her podcast Business Unusual, Corcoran answered a listener's question about making a good impression with hiring managers.

Corcoran shared one of her biggest interview pet peeves: candidates who clump into an interview wearing teetering high heels. She doesn't even look at their resumes. They go straight to the "no" pile.

She simply doesn't think that such a person would work very hard if she were to get the job. Maybe it's too harsh of a rule, but Corcoran says it's still important to consider how you physically represent yourself in an interview. First impressions count for a lot.

Not letting your age define you

The 24-year-old listener was concerned she was being passed over for roles she was well qualified for because of her age. How could she better show she was fully capable of senior roles in just a 20-minute interview slot?

Corcoran acknowledged that youth can be a disadvantage in a job search. But she doesn't believe you need to be older to be smart. She encouraged the listener to come prepared with a succinct story that shows her maturity in the workplace before the hiring manager has a chance to discount her for it.

Dressing the part

If she wanted to come off as more put-together than a typical 24-year-old, Corcoran advised her, she needed to dress like it. Corcoran suggested she invest in quality pieces that project professionalism.

"Edit your clothing to look like what that person who's interviewing wants to see," she said. "If that requires that you dress a little bit older, then by all means go out and buy that 'old' outfit."