Why does Odysseus disguise himself as a beggar?

Odysseus is disguised as a beggar by the goddess Athena, who is helping him plot his revenge against the suitors who are courting his wife. From the vantage point of a beggar in his own court, Odysseus is able to assess who remains loyal to him, who the suitors are, their habits, and he is able to sow dissent amongst them. The information he gleans allows him to formulate a plan for revenge.

Agamemnon's warning also causes Odysseus to be weary in returning home as himself, as he does not know if his wife is true and on his side yet. Odysseus also is able to see if his wife has remained loyal to him after all these years.