What is some evidence that Odysseus is a good or bad leader in Homer's Odyssey?
Determining whether Odysseus is a "good" or "bad" leader is a difficult question. On the surface, he probably appears to have more lapses as a leader than successes.
In Odyssey 9, he refuses to leave the cave of the Cyclops, despite his men's urging to the contrary.
"At first my men begged me to take some cheeses and go, then to drive the lambs and kids from the pens down to the swift ship and set sail. But I would not listen, though it would have been best, wishing to see the giant himself, and test his hospitality" (A.S. Kline translation)
This choice results in the death of six of his men.
In Odyssey 10, Odysseus does not communicate with his men about the contents of the bag he receives from Aeolus. Odysseus falls asleep, his men become curious, open the bag just when their ship was in sight of their homeland, and then they are blown back to Aeolus' land.
In Odyssey 12, Odysseus does communicate about the dangers of eating Helios' cattle, but he again falls asleep. This gives his men the chance to eat some of the cattle, which results in their lives being lost.
On the other hand, Odysseus does seem to make the right choice in Odyssey 12 when faced with the Scylla and Charybdis. He sails nearer to the Scylla, which does result in the deaths of six more crewmen; but, if he had sailed closer to the Charybdis, the entire ship would have been lost.
Also, in Odyssey 12, Odysseus probably prevents a significant loss of life by having his men stuff their ears with wax while sailing past the island of the Sirens.
Odysseus' leadership choices seem to be better once he returns to Ithaca. He wipes out the suitors and all of his allies (Telemachus, Eumaeus, and Philoetius) survive the fight.
Thus, when it comes to Odysseus' leadership qualities, Homer presents us with an ambiguous picture.