Why did Sai Baba appear as a different, unknown Fakir to Appasaheb instead of in his usual form?

The text in Chapter 33 suggests that Baba's appearance as an unknown Fakir was a deliberate test for Appasaheb. After Appasaheb made the vow to give ten Rupees, Baba came to collect. By appearing as a stranger, Baba tested the purity and steadfastness of Appasaheb's promise. It was easy to give to the known and beloved Sai Baba, but would Appasaheb honor his word to a seemingly random beggar? Appasaheb's resulting suspicion and hesitation revealed his human fallibility. The text poses a rhetorical question: "why would Baba come in Fakir form? If it weren't a pretext for Dakshina, what flavor would come to the story?" This implies the entire episode was orchestrated by Baba as a pretext to teach a valuable lesson about keeping one's word regardless of the circumstances.