How "clean" is your cast iron?
I recently got a few cast iron pans (two skillets and a grill pan) and love how they cook, but the whole cleaning situation I can't quite get because of the instructions to not use soap. I have a dedicated brush for scraping clean the cast iron, but no matter how clean it looks, when I dry it with paper towels, I always get brown residue on the paper towels. This is especially the case for the grill pan.
Is your cast iron as clean as your other cookware like non-stick pans and stainless steel pans? I just don't see how it's possible without scrubbing with soapy water... Especially when there isn't visible dirtiness on it, it's like that brown/food residue is cooked onto the cast iron. I suppose it shouldn't be an issue since I pre-heat my cast iron to very high temperatures whenever I use it for searing meats, but it's just a little disheartening to feel like my cookware isn't clean.