For being too technical and in depth?
Yeah, I kid you not! I got gigged for 25 points on a research paper for Oceanography on Freshwater Fish Parasitic Diseases. That was my assigned topic. I approached it from an Epidemiological perspective, utilizing study resources from well documented studies in SE Asia, The US, and Africa, and even tied it up neatly with long term effect of undiagnosed parasitic infections in US immigrants. Blahhhhrg!
Still a very solid A, but I really feel like I got gigged just for the sake of getting gigged for points.