What details of this speech show that Polyphemus is far less clever than Odysseus?

Polyphemus is easily outwitted by Odysseus when the latter tricks him by giving a false name ("Nobody"). Additionally, Polyphemus falls for Odysseus' plan by believing that the sheep in his flock are actually his men escaping. Lastly, his boastfulness and lack of insight make him vulnerable to Odysseus' cunning tactics.