How can you tell when buttermilk goes bad?

I’ve wondered the same about sour cream.

mold? I am a bad fridge cleaner.

Maybe it smells both sour and bad. Sour cream grows mold, and sometimes get this red stuff all over it. It looks really evil. I’m sure buttermilk starts looking and smelling evil when it’s really, really bad. I don’t know how you can tell before that.

It really, really smells.

It gets lumps in it and develops a bitter taste. Eventually, it turns solid. I know this from personal experience.

@Darwin, ah that makes sense. The weird thing is I’ve had old cream get a bit lumpy, but the lumps appeared to be butter.