What does Genesis 13:13 mean?

When it came time for Abram and Lot to go their separate ways in the land God had promised to Abram, Lot chose to settle in the well-watered valley along the Jordan river. That made sense in a land prone to occasional drought. From a material standpoint, this was a wise choice. Lot's new land was exactly what his growing family and flocks needed.

However, Lot's choice to pitch his tents near the city of Sodom was clearly spiritually unwise. At the very least, Lot does not seem to have taken the threat of Sodom's depraved culture seriously. We're told nothing about Lot's motive for settling his tents so close to the city. More than likely, there was no absolutely necessary reason to do so. Later in Genesis, we will see Lot and his family actually move into the town itself. This gradual numbness to evil will lead to Lot's tragic fate (Genesis 19).

Lot most certainly knew that the people of Sodom were wicked, as this verse reveals (Genesis 13:10). God was certainly aware of their great sins against Him. Later in the book, it will become clear that those sins included participating in homosexuality and rape, among others (Ezekiel 16:49–50).