Meagan Good plays a gorgeous cop gone undercover with a rich family in NBC’s new drama, “Deception.” And she’s been going undercover after-hours too, Page Six has learned exclusively, partying not-so-under-the-radar at grimy Brooklyn dive, Alibi. The basement spot, located in the actress’ adopted neighborhood of Fort Greene, features a sticky bar and icky bathrooms, but it’s still proved an attractive destination for Good in recent weeks. “She’s usually really low-key, wearing a beanie and not too much makeup,” a source who’s partied with the star tells us. “But she’s so stunning, it’d be impossible to miss her.” For sure, that’ll be even more true after her show premieres on NBC tonight at 9 p.m.