Final answer:
The 'bad luck' Sanchez thinks of is likely referring to negative or unfortunate events but is not specified in the provided excerpts. The concept could relate to a mismatch between expectation and reality or unintended negative consequences following positive events.
Step-by-step explanation:
The "bad luck" Sanchez thinks of is not explicitly mentioned in the provided excerpts. However, based on similar contexts from different texts, it may refer to a sense of misfortune or unexpected negative outcomes that contradict someone's hopes or expectations. In the snippet referring to an unspecified presidency, the "bad luck" seems to be the ironic twist of needing a philosophy opposite to the one that secured election victory.
Similarly, Choe's response about Tang's bad luck spreading could imply the unintended negative consequences following a period of cultural flourishing. Additionally, the excerpt from the conversation between Nora and Mrs. Linde touches upon contrasting fortunes when Nora talks about her husband's good luck of being made manager of the Bank, which may also highlight the variability of luck or fortune experienced by different characters.