I have always taken the tack that if a reader misses something or gets the wrong end of the stick, I just haven't emphasized that point strongly enough. (If a reader is simply skimming, well ...the story might be boring—which is my problem, but a different one—or they might just be the wrong reader for it.) If the beta has been reading closely, though, and still missed something important—even if it's only one reader out of ten—I will go back and attempt to strengthen that point. If it's something that can be slightly expanded, such as adding another couple of sentences before moving on, that often works. For example, instead of saying something to the effect that the Jenna noticed Karen rummaging inside a bag, you can make this into a slightly bigger deal. You can mention Jenna's puzzlement as to WHY Karen would care about what's inside an old, discarded bag. Or Jenna could reflect, with some amusement, that Karen could never keep her nose out of somebody else's private stash. Or you could have Jenna watch as Karen pulls rubbish out of the bag and throws it behind her, like a baby rooting through a box of toys. It doesn't have to be a big deal at the time, if you don't want to give away too much, but just make sure that when the rummaged bag DOES become crucial to the plot—fifteen chapters later—that the reader will remember the incident. If you just casually mention that Karen rummaged through a bag, that incident might not stick. A point can also be reinforced simply by referring to it more than once. If a reader has read carefully but has come to the wrong conclusion, then that also needs attention. You won't always score, but it's a good idea to work on it. Otherwise, what's the point of a beta? Why did they get the wrong idea? See if you can figure it out, then focus events in the story more strongly, so they inevitably lead to the conclusion. I've always maintained that your story is inside your head. The job of a writer is to make that story come alive for somebody else. And to do that, you need to master the fine art of communication. Not everybody will 'get' it, of course. But I'd say don't be quick to dismiss people who aren't quite there. Unless they are deliberately picking fault and don't want to like your story, it's always worthwhile to try to bridge the gap between your brain and theirs. The one thing I do dismiss from a critique, however, is anybody's attempt to get me to tell a different story. People who decide they don't like my characters for what they are, for example. It's different if they get the wrong idea about what my characters are like. Then I'll try to make changes to make the characters' actions and motivations become more understandable. But if the beta just doesn't like them?—would never like them, no matter what? That's fine. It's my story. I'm open to trying to tell it differently, but not to change what I'm telling. That would make a different story altogether. And that's not why I write.