In The Odyssey, is the cyclops a good host or bad host? Why?

Polyphemus, the Cyclops and son of Poseidon, is a terrible host.  He is described as "lawless," but that doesn't quite do justice to his true nature.  In Ancient Greece, the highest law was known as Xenia.  Xenia is the ancient Greek word for "hospitality."  This law declares that any traveler is to be fed, sheltered, and taken care of by the inhabitants of a home.  It is protected by Zeus himself.  In many stories, people attempt to "get around" the concept by sending guests off on what are thought to be impossible tasks, hoping that the guests die in the process.  However, Polyphemus takes it to an entirely different level, and suffers terribly for it.  

This law is so well known and universally obeyed that Odysseus naturally assumes that entering Polyphemus's cave and eating from his table is perfectly acceptable, even though the Cyclops isn't at home when he and his men arrive.  In fact, when his men wish to return to the boat, he wants to wait for the Cyclops to return because he believes that Polyphemus, being a good host, will also present Odysseus with a gift.  When Polyphemus returns to his cave, he rolls a huge rock in front of the door to keep his sheep in.  He then notices Odysseus and his men.  Odysseus introduces himself and says

"But chancing here, we come before your knees to ask that you will offer hospitality, and in other ways as well will give the gift which is the stranger's due.  O mighty one, respect the gods.  We are your suppliants, and Zeus is the avenger of the suppliant and the stranger; he is the stranger's friend, attending the deserving."

Odysseus asks for Xenia, evening invoking the name of Zeus, but the Cyclops responds that his race "pay no need to aegis-bearing Zeus, nor to the blessed gods; because we are much stronger than themselves."  Polyphemus then eats two of the men; he eats two more for breakfast the next morning and two for dinner.  This is not the behavior of a good host, or even a mediocre host.  Polyphemus eats his guests, directly defying Zeus, and says that he is stronger than the most powerful god.

Polyphemus ends up paying for his actions and words as Odysseus thinks of a way to trick him.  Odysseus shares his wine with Polyphemus, eventually getting him drunk.  Once the Cyclops falls asleep, Odysseus and his men pull out a piece of the Cyclops's club they had sharpened, charred, and hid in the dung around the cave.  They then reheat it and use it to stab him in the eye.  There's a lengthy description of how terribly the Cyclops suffers as a result of being stabbed with the flaming stick, and Odysseus and his men sneak out of the cave by attaching themselves to the underside of the Cyclops's giant sheep.  Unable to see them because he is now blind, Polyphemus has no idea they are under the livestock, and the men quickly escape to the sea.

If Polyphemus had simply shown respect to the gods by obeying Zeus's law of Xenia, things would have turned out much differently for him.  Instead, he is one of the worst hosts ever and is left blinded, humbled, and sheepless because of it.