Again, this sounds like an oxymoron.
With flat plate printed stamps in particular, the gumming process was never an exact science. Sometimes the gum ran well into the margin area. Sometimes the gum fell a little short of the margin area, leaving parts of the stamp ungummed. Sometimes the edges of the gummed area may have uneven application, leaving some ungummed areas that may or may not fall into the stamp area.
Some dealers call these stamps NH. Technically, that is true because the stamp has never been hinged. However, I think that is a bit deceiving because the stamp has some areas where the gum is missing.
The reason collectors distinguish between NH and hinged stamps is because the hinging process disturbs (or removes) some of the gum. Because the gum isn’t 100% pristine, that lowers the value of the stamp. Are ungummed areas on a stamp the same thing? Yes, they are naturally occurring because of the stamp production process. But it’s the same result in the end – an area of the stamp where the gum isn’t 100% pristine.
I have a confession. When the gum comes up to the very tips of the perforations and maybe the very tips of the perforations are missing a spot of gum, I still call that a never hinged stamp because it’s 99.99% of the way there and it’s naturally occurring. This is my own opinion and I don’t think a few tiny spots of missing gum on the perforation tips is a matter worth mentioning. Some people may disagree with me.
However, when a stamp has any ungummed areas, I figure that into the value of the stamp. I treat that stamp as a hinged copy. Not all dealers do this and they use the price of a never hinged copy. Some dealers will classify the stamp has never hinged but note in the description that there is a gum skip. Some dealers feel this is naturally occurring and don’t mention it. There is no consistency in this area. I tend to be conservative and describe and price my stamps appropriately.