How do you clean these damn things?

[capnhowdy]

I love to cook. Lots of time in cast iron pots, which is indicative to the south, so I hear.
I have scores of these that I have semi-retired because they started looking, well, kinda nasty.
I'd like to use them again but don't have a clue how to clean them up.
Forget soap & water. Tried that. I've heard lots of myths on this procedure, but would like to hear from someone who has actually been there, done that.
Some of them are really old. I've heard the older the better, so there's got to be a way to clean those babies up. I guess I'm not the only one who uses them, and for that matter, needs to know.
If noone does know, it will be the first topic Ive ever seen on the Cellar to fit that category..............