One that has a coating of cooking on it.
I don't think it helps with things like temperatures, but I do think it helps with things like fly ash.
Not sure what major is, I do want to make sure there is never standing grease in my pit or I certainly will have a fire. Not sure if it is soot, but there is definitely a black substance in the smoke if I do not.
It might, not sure how to quantify it.
Which brings up the questions:
What is a seasoned pit?
Why does it improve performance in your cook? Or does it really do that?
If you don't do a major clean what happens? Do you get soot into your cook? Fires?
Seems that some of the best BBQ joints I've been to have big heavily soiled stick pits that don't look like they've been cleaned ever. Does that have anything to do with the taste of the BBQ? Or if not then why worry?
Just a few valid answers would be appreciated.