Studio DEEN/YMMV

Memetic Mutation: A lot of infamy has been gained by their bad animation.
Never Live It Down: While they have produced a lot over the years, many won't forgive them for their more Off-Model visual adaptions like Fate/stay night, Axis Powers Hetalia, and both Higurashi: When They Cry and Umineko: When They Cry (to the point of Memetic Mutation with the latter).
The Scrappy: Let's just say there's a very vocal regiment of people angry at their adaptation quality.
Special Effects Failure: This one frame instance in Mon Colle Knights episode 2^[1]. Even AKOM had the decency not to include production info within the animation.