If we follow the chronology of Odysseus' adventures as he tells them beginning in Odyssey 9, we and Odysseus learn that telling the truth is not necessarily the best course of action. This is especially true with respect to Odysseus' identity. In Odyssey 9, when Odysseus reveals his true identity to the Cyclops, this leads to Odysseus suffering greatly at the hands of Poseidon. After that point, I would say that Odysseus was very careful to conceal his identity and such concealment involved him telling false stories. I would say he creates these falsehoods primarily because he needs to, not necessarily because he likes to.
Although some modern readers are upset with Odysseus because of his frequent fabrications, few of us have to face the frequent threat of death that Odysseus did. Odysseus had been away from home for 20 years and a lot could have changed in that time. Odysseus had to be careful about what he said and to whom he said it.
Finally, we should also note that the gods themselves seem to endorse Odysseus' deceptions. Consider Athene's words to Odysseus after he tells he a false story in Odyssey 13:
We are well-matched in these arts, you being the most eloquent and practical of men, and I known among the gods for my wisdom and subtlety. (A.S. Kline translation)
We should also note that in Odyssey 13 Athene herself commands Odysseus not to reveal his identity until the right moment:
Tell no one, man or woman, that it is you, back from your wanderings...
Thus, the gods themselves seem to both approve of Odysseus' deceptive nature and to insist that he take evasive verbal measures.