I mean, really bad. I have retards for co-authors. There's 4 of us in a paper I am leading, the other 2 are ok and both do work and do good work. The fourth is a f**ing lemon. Randomly adds stuff to the paper in places it doesn't belong. Has no idea what the paper is about and I have to explain every detail to him like he's from China (well, he is) and tell him what to write. Then he proudly writes what I told him to write, without citing anything in support of his arguments, and pretends like he did work.
This guy is useless and a drag on the paper. What to do in such a situation? The other two coauthors like him so they want to keep him on, but I want to tell them to drop this useless bag of bricks from the paper.
How to handle such a situation?