Can cultures be immoral?

We make moral judgments about people and actions all the time. Things get more complicated when the subject is an entire culture.

Can a culture itself be cruel, unjust, or immoral? Or can we only make those judgments about particular beliefs, institutions, and practices within it? How do we take cultural difference seriously without giving every practice immunity from criticism?

And who gets to judge, especially when people within the same culture disagree with one another?