Pot scrubbers. Every so often you need one. But...you don't need to buy one! Here's the free options that we use.
1) Square Bag Fasteners. You find them on bread bags or potato bags. They're the perfect strength and size to scrub small spots.
2) Tomato bags or onion bags. We roll up our dishtowel and pop it in an onion or tomato bag. It works perfect for larger areas that need scrubbing.