Big Timers (1945)

A wealthy young society man is dating a beautiful young woman who he believes is also in his "class" because of her beautiful, classically trained singing voice. In actuality, she is the daughter of a poor hotel maid, and in order to keep the boyfriend from finding out just how poor the family is, the mother manages to get a fancy room in the hotel to try to convince him that her daughter is "good enough" for him.