one of my favorite stories actually...basically, Lot was the most decent person in Sodom and Gemorah..and when you parallel him to Abraham..Abraham was the most decent person on his part of the world. However, Abraham's decency and morality was much much higher relatively to Lot.
If you read the story in the beginning, Abraham greets his guests in a much more honorable way compared to Lot. He picks the best meat and cakes for his guests, while Lot prepares unlevened bread.
When the Sodomites threaten to knock down Lot's door to rape the angels, Lot offers up his daughters instead of the guest. That's a horrible thing to do to offer either! It might show that Lot was affected by his society.
Lot's wife looks back when the city is being destroyed. This might be figurative to her not wanting to let go of that old society..and therefore she was nothing more than a pillar of salt.
When Lot goes to caves to hide, his daughters are kind of pissed that they have no one and so they make their father drunk and end up comitting incest with him so that they may have offspring. The offspring of Lot became the Moabites...the Moabites were enemies wtih the Israelites.