The Bellboy and the Playgirls (1962)

The bellboy aspires to be a private eye and is reading a book to learn the trade. The 'suspicious' activities of women in the hotel give him a chance to practice his skills. Surprise! They are representatives of a lingerie manufacturer. To investigate further, he poses as a potential buyer, and the women take turns modeling their wares. This includes demonstrations of how easily the garments come off - making this a film destined for softcore movie palaces in the '60s.