Cooking beans even in a non-stick pot can cause stains that will not scrub out. If you wash the pot, then pour vinegar in the pot, it will clean stainless steel and Teflon pots clean.

Cooking a tomato based dish in the pot will do the same thing.

You can also remove dried on food from plates pans and dishes. If the food is really stuck fast and burnt on sprinkle cream of tartar on the area and then spray with white vinegar. Just wipe off and rinse.