You know the kind. When a promising idea is written in a story that is either too short, very poorly written, or lacking in so much detail that it's mostly dialog. The last one being especially important if the story's topic is particularly angsty, but most of it is reduced to dialog when maybe more detail directed toward what the characters are doing or even how their voice tones should sound could make a world of difference to how a scene could be perceived.
Also: one-scene stories that lack any detail at all. Now, keep in mind they're not all bad. Some people can pull them off. For instance, childishgrin is one of the few writers who can do a one-scene, mainly-dialog story and have it come off sounding halfway decent. Sadly, though, many writers who try fail. And it's sad to see.