The ninth book of Homer's Odyssey provides an excellent example of how a host should NOT treat his guest. Typically, a good host in the Odyssey offers his guest food and drink before even asking the guest his name or his business. In addition, the good host may also offer his guest a bath, lodging for at least one night, and will also give his guest a gift when the guest leaves.
The Cyclops Polyphemos does none of these things for Odysseus. The Cyclops asks Odysseus his name immediately, and obviously he does not give Odysseus food and drink, but instead turns Odysseus' men in to his own food. Furthermore, it is Odysseus who gives the Cyclops something to drink. The Cyclops' "gift" to Odysseus will be that he will eat Odysseus last of all. A good host would also have reverence for the gods. Polyphemus expresses the opposite:
Stranger, you are a foreigner or a fool, telling me to fear and revere the gods, since the Cyclopes care nothing for aegis-bearing Zeus: we are greater than they. I would spare neither you nor your friends, to evade Zeus’ anger, but only as my own heart prompted. (A.S. Kline translation)
In ancient Greek culture, one of the most important values was xenos, or hospitality. The relationship between a host and their guest is absolutely sacred. This was so important, in fact, that Zeus (in the form of Zeus Xenios) was the god of hospitality, and would avenge any guest who had been mistreated. The Cyclops Polyphemus exemplifies the breaking of xenos, which was considered very barbaric and uncivilized.