I don't blame you Sarah. Look at, well, this comment thread. Some, perhaps most of the comments are fine. And some are rubbish.
To everyone saying she can block or report them... sure she can. But given how many people do this you're basically asking her to spend a fair bit of time doing that. It's also not really a scalable solution. Could Sarah block 5 commenters a day? Sure. 50? um.... 500? No. As G+ grows, this will become a significant issue for people like Sarah who are fairly prominent. It also means that the comment threads are MUCH less useful for those of us who'd like to actually discuss a post. I find myself spending far less time on G+ threads because I just don't want to wade through all the crap.