I have never thought about it critically, but I do have five or six pipes from various brands and artisans that have partial rustication, where the bowls are finished smooth but have areas that are rusticated. Presumably most or all of these cover areas that would otherwise show flaws and fills, but instead have accents that I find quite pleasing. Then again, I don't mind fills if they are done tastefully and on pipes that are priced lower accordingly. Do you reject partial rustication out of hand, tolerate it, or find it pleasing if done well? I will say that most of my partially rusticated pipes have other distinct virtues in terms of fit and finish, light weight, size bowl, etc.