I keep a gallon of vinegar under the kitchen sink pretty much all the time. It’s an extremely useful cleanser, especially in conjunction with baking soda or a dash of salt as a mild abrasive. It’s also a weak acid (duh) and thus useful for loosening or degrading any number of things – like an old, thick coat of paint covering metal clothes hooks.
Soaked in vinegar overnight, the paint rubs off with my fingers.