仄暗い appears in the title of a book by 鈴木光司 (仄暗い水の底から, it was made into movies in Japan and the US), and I've seen the expression とりたてて...ない used more than once in books intended for primary school children, so I don't think that they are all that uncommon. Besides, since 仄暗い is simply 暗い with a prefix, and とりたてて is a sentence adverb, one can easily grasp the meaning of the sentence without knowing those words, and it's not all that hard to figure out their meaning from the context.