Why speculate? We have a good example in Oedipus. The king has unwittlingly married his mother, and the city of Thebes receives a plague as a result. The seer, Tiresias, tells Oedipus that his blindness will be his undoing and that he will be cursed for his incestuous, patricidal actions.
So, it depends on the weight of the taboo and the status of the accuser. If it is a well established taboo, and if the accuser is a priest, priestess or oracle, then yes, we have to obey or suffer the curses of the people and the gods.
If, on the other hand, we are powerful enough, we can flaunt the customs secure in our knowledge that our protecting gods will avert the curses. Menalaus and Nestor both returned home to Achaea, even after defiling the altars of Apollo at Troy. Lesser heroes, like Agamemnon, died the death.