Some further information and open to correction if I'm wrong :sun:
polishing the pontil mark is a final finishing step- but it requires an extra step in the process of making the piece, which takes time and time is money. So I think, 'generally' speaking, the best producers polished their pontil marks or ground and polished the base of the piece. Others ground out the rough snap off mark but didn't do the further step of polishing and yet others leave it just snapped off.
Obviously there are some that snap off the pontil mark neatly, others not so.
However.... all this said, there are caveats - some very expensive pieces have a snapped off pontil marks, left unground and unpolished. Equally studio glass makers often either leave a (mostly neat in my experience but not always) snapped off pontil mark, or grind the base of the piece and don't polish it. So I guess really what I'm saying is that as I understand it, a pontil mark alone cannot be the only thing to judge a piece on. The whole piece, finish, effect, decor, quality etc, has to be looked at to be able to judge where something may have been made

As I said, I'm open to correction.
m