What does Genesis 18:22 mean?

In the previous verses, the Lord in human form had revealed to Abraham His plans for the cities of Sodom and Gomorrah. As they stood at a high vantage point overlooking Sodom in the distance, with two angels standing nearby, the Lord told Abraham that the sin of the people of those cities was very great. The outcry of their victims had reached His ears. The Lord was preparing to go and see the city for Himself to confirm what He had heard and, by implication, proceed with executing His judgment against it. All of these are stated in human terms, in order to highlight God's point. Like a parent who already knows what has happened, God asks rhetorical questions and speaks of "investigation" for the sake of His children.

Now the two angels turn and walk toward Sodom. Abraham and the Lord remain where they are. Abraham's nephew Lot lives in the city, and Abraham is about to question the Lord more specifically about Sodom's future. The answers he receives will not be pleasant.