1. Overspecialization. We are so focussed on very narrow questions, that the big picture often disappears from view. The overspecialized writer knows so much about the subject matter that it becomes impossible to tell what the audience knows or doesn't. He or she doesn't put himself in the position of the reader. (Pinker on the "Curse of Knowledge.")
2. Low Information. There will often be a small amount of actually significant information per page. All the findings are there, however insignificant. The same points will be repeated endlessly, using similar language. I often start reading a book on page 101. By then the writer has to have gotten into the subject matter.
3. Low stylistic intensity. Writing is dogged, perfunctory, lacking in energy.