Red dresses are commonly used and have historically been used in poetry and music as a symbol for prostitution. With that in mind, look at the song again. Although Justin is not singing about a prostitute, he is clearly singing about how he enjoys the sexual aspect of a relationship more than the emotional.
i.e.
"with tilted head like a listener
but i'm just thinking about the red dress"
he's pretending to be listening to the girl, but in reality he is just been thinking about sex.
Red dresses are commonly used and have historically been used in poetry and music as a symbol for prostitution. With that in mind, look at the song again. Although Justin is not singing about a prostitute, he is clearly singing about how he enjoys the sexual aspect of a relationship more than the emotional. i.e. "with tilted head like a listener but i'm just thinking about the red dress"
he's pretending to be listening to the girl, but in reality he is just been thinking about sex.