We're huge fans of having vinegar in our cleaning arsenal. It's great at lifting stains, freshening laundry, cleaning windows, and much more. Plus, it's inexpensive and all-natural. But vinegar is also acidic, which means that you can't quite use it everywhere. Skip it on these spots: 1. Granite and marble countertops. The acid in vinegar can etch natural stone, says Carolyn Forte, director of the Home Appliances and Cleaning Products lab at the Good Housekeeping Research Institute.