There is some doubt about whether this is scat singing, which was certainly fashionable about this time. Some think it is. It is the art of creating an instrumental style improvisation vocally, relating less to identifiable words than the tone and articulation of instruments. From this definition, Helen Kane was not singing scat, though she may have been influenced by it. But whatever Helen Kane was singing, whether it was scat or whether it wasn't, it was certainly a novelty in the 1920s, though the same technique had been practised in English music halls in the 1870s and later, when much of the spoken business was ad lib and the singing was often done under the influence of strong liquor.
Every song is polished and honed.
She knew exactly what she was doing. Probably even when she got married in the same year as Good Boy to a fellow entertainer in the show, Dan Healy. Inevitably in 1929 she went to Hollywood, full of well-grounded hopes, and equally inevitably it was Paramount which signed her on. It was a time when Paramount were turning out modest undemanding films like sausages. Paramount Pictures Corporation was the creation of Adolph Zukor, a nickelodeon showman who in 1912 founded Famous Players, with the firm intention merely of presenting stage successes incinematic form.