The odor of spoiled milk is traditionally very difficult to remove. Fortunately, there are some relatively simple (and inexpensive) solutions. The sooner you clean the smelly spot, the greater your chances of restoring a fresh scent to your house-on-wheels.
Blot up any remaining liquid with a towel.
Pour baking soda over the area where the milk was spilled.
Sprinkle cold water on top of the baking soda.
Let stand overnight.
Vacuum to remove baking soda.
If the smell remains, try treating the area with white vinegar. Let sit for 15 minutes, then blot excess vinegar with paper towels.
If vinegar fails to beat the stink, tackle it with an enzyme odor remover. These products use biological organisms that consume odors and can be found at stores that specialize in cleaning products.
Use a commercial leather cleaner and odor eliminator on leather upholstery. Your dealer may carry these products.
Allow the area to dry completely: residual moisture can cause mildew. Use a hair dryer or fan if necessary, being careful not to scorch carpet fibers with a hair dryer.
If the smell is limited to a floor mat, it might be easier to replace the mat with a new one. Consider applying a product such as Scotchgard to cloth upholstery and carpets to repel stains. Use Scotchgard Leather Protector for leather upholstery.
If a substantial amount of milk has spilled and gone sour, or if the milk has soaked deeply into the seat or carpet, you may need to seek professional help from an auto detailer.