My ex wife had leather interior in a car. The little one had left his sippy cup upside down and it leaked. Yeah, milk soaked into foam in july = not cool at all. I had to pull the back seat out and drench it in water to get the milk out then threw almost an entire box of fabric softener sheets under it to remove the stench.
Tip of the day: Fabric softener sheets will remove bad odors from anything!