Will firing flaws seriously devalue pottery ?

Bought another goblet/chalice today, it is by Porthmadog Pottery. It has no damage as such but the glaze on the inside of the cup is flawed, it is only the size of a pinhead (a term my brothers used on me when we were younger) will this be detrimental to it value ?

Generally speaking yes it will, however on some types of glazes rough stoeware etc. it wouldn't matter as much IMO

Many thanks, Ed.

some firing flaws can even ADD value - early English porcelain from companies like New Hall, inevitably have specks of ash caught in the glaze because of the firing processes used at the time. Without such "blemishes", it can make it harder to tell the fakes from the genuine thing. I positively encourage buying ceramics with firing flaws as at least you know it is an 'honest' fault and not a chip or crack that someone's tried to cover up.

I agree with you, I think they add interest to an item.
Thanks Bistoboy.