My AW was like that also, loved to complain about everyone, what faults they had, how they looked, ate, talked, lived, you name it. She did this sober or drunk. I think they are trying to build themselves up by putting other people down.
The other thing I find amazing was she would sit on the sofa, all messed up, watching one of those intervention shows on TV. The irony of it just rolled off her back.
Your friend,