Before buying used cookware, check these things to inspect on a second-hand cast iron pan. Look for cracks, warping, heavy rust, deep pitting, rough cooking surfaces, strange smells, and handle damage. Light surface rust can often be cleaned, but cracks and serious warping are usually not worth the risk. Place the pan on a flat surface to see if it rocks, and check whether the cooking surface feels usable. Also consider how much restoration work you are willing to do. A solid used cast iron pan can be a great kitchen find.