Debbie's problem is exactly what makes me use the Friend Lists feature of Facebook. It might not protect your data that well, but at least it is able to keep things semi-private from the (less tech-savvy) friends of yours from other social circles.

But, of course, Facebook screws you in the end. Even you choose exactly what friends see that photo of yours, and what friends see that wall post, you happen to comment on a friend's photo and then everybody sees it.

And it also does nothing about friends of yours from some circle deliberately accessing the profiles of the people from other circle and seeing everything you didn't want them to see (like tagged photos of yours that they couldn't see on your profile because you forbidden them to).