I don't know what "snot" is but here is the McMillan/Gonzalez "Speedy Formula"

http://www.varminthunters.com/tech/sgycleaning.html

I realize this is a pretty simple, basic question for this esoteric discussion thread, but here goes anyway. I was taught to clean a rifle barrel with #9 and a patch and leave overnight. The next day, if a clean patch comes out green/blue then there is still copper in the barrel and to repeat the process until the next day patch comes out clean. If this does not happen in a few days then a brush wet with #9 can be used (minimally). The barrel is assumed to be clean when the patch comes out clean after an overnight soaking.

So how can I tell if there is carbon fouling? I can't see it or feel it. What am I missing here after all these years?

MikeM.
I do a similar thing when the rifle hasn't been fired much, or doesn't pick up much copper, and always keep getting some black marks on the patch, which I've assumed is the carbon getting soaked out gradually.

When bad, I sometimes get some "slivers" of black shiney stuff like pencil lead.

When I get nothing after a week or so of soaking in Hoppies 9 I assume it's clean.

What about throughly cleaning the bore down to the base metal and then appling a moly coat treatmnent?
Maybe less carbon and copper would laminate them selves to the inside of the bore it it was so treated, or at least the fouling might be more easily removed.

I am reminded of an new cast iron frying pan that must be seasoned before use, by coating it with oil and baking in an over until there is a hard black baked on carbon coating all over it.

Maybe a moly coat would be similar.