Yes, I think you have some confusion as to baked on crud and seasoning. I fill my pans with water, put on the stove to boil and then dump the water down the drain and go to the pan with a paper towel. The crud comes off and all that is left is cast iron (seasoned of course). If there is anything left on the pan I put some kosher salt in it and scrub away. After all that I rub down the pan with cooking oil.
When finished the pan should look like this:
Granted the bottoms of some of my older pans (50 or more years old) have layers of cooked on crud, but the insides look like the picture.