Help with Questions to The Odyssey: In the 14th and 15th books, Odysseus and Eumaeus exchange life stories

In the 14^th and 15^th books, Odysseus and Eumaeus exchange life stories, with the disguised king lying (as he so often does) and Eumaeus telling his true history. How does the theme of deceit and lying figure in these tales? Why does Odysseus wait so long to reveal his real identity to Eumaeus? Does his deceit and manipulation seem justified?