It can be either good comment or bad one. If he likes to hear it, he says that sentence but inside he smiles. If he hates it or doesn't like her, he doesn't want to hear it again... For example, if I ask a guy for a coffee or drink with a lot of pulling and over-smiling(?), he could say '어디서 앙탈이야!' Then I could just say sorry and walk away...hahaha Or between a couple, the guy would say it as a meaning of 'how cute you are!'