Barbara Corcoran says this is the No. 1 mistake new home buyers can easily avoid: 'Go back for another look'

In a Good Morning America appearance earlier this year, Corcoran doubled down on that advice, saying it's essential to know what the house you may have viewed in the early afternoon looks like at all times of the day.

"People fall in love with the house and think at that moment in time it's their new house," she said. "No, you got to see it in the morning and you got to see it at night. Do your snooping."

Mike Biryla, a real estate agent at The Agency, agrees with Corcoran that going for another look before signing on the dotted line is worth it. And what you should be hoping to feel then is the exact same feeling you felt the first time you viewed the space and decided it was the right one.

"You get to walk the space again and reaffirm that your intuition and feeling about the space was correct," he tells CNBC Make It. "When you go back for a second look, it should be to make sure that the floor plan makes sense for you."

Biryla added that he always tells his clients that the second look isn't about measuring every inch of the property but more about looking for the little things you may have missed on the first walkthrough, like small imperfections or anything that might need a repair, and getting a general flow.

Biryla tells CNBC Make It that it's also important to spend time in the area, neighborhood or building and talk to people living there, especially if you're buying an apartment.

"Sit in the lobby; it's a way to see some of the potential owners coming in and out and chatting with some of the staff to get a flow for how the building is run," he said. "I always recommend checking the basement of a building because it can tell a lot about how the place is run."

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," which features Barbara Corcoran as a panelist.

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