Those stats are quite scary with extremely high bounce rates.
Don't be so quick to paint with a broad brush. Everything is relative.
I have some sites with extremely high bounce rates (80%+), but sometimes that's just the nature of the content.
For example, if someone wants to learn how to cure a [insert painful medical ailment here], they're not very likely to spend a whole lot of time browsing your site. They have some more important things to do...
Obviously, I'm not saying a high bounce rate is good. But I am saying that sometimes a high bounce rate is entirely appropriate, depending on the keywords that are driving traffic.