Personally, I'm the only one I work with to have my screens facing out to the public eye. Hiding behind screens just invites distractions. There's nothing that could be on my screens that is sensitive enough to hide. Even if other developers saw what was there, the worst that could happen would be 5 minutes trying to explain what a specific core function did, and an hour wasted trying to get out of a trivial one sided conversation about conspiracies all stemming from how their component doesn't handle multibyte characters and how they have to strip them out (yeah don't ask, just don't... best not to).
Reading newspapers over someone's shoulder is frowned upon and is considered bad manners. You can apply the same analogy here as well. And use common sense in such conditions. Not all matters are binary.
In your case, you can purchase privacy overlay screens and apply them to your monitors if you don't feel comfortable sharing yours.
IME, the people who have a problem with it are either 1) doing work that shouldn't be on an outward facing screen (for example, working with sensitive data) 2) doing things they probably shouldn't be doing or 3) people who are a bit sensitive that they think everyone's thinking that they're a 2 if they happen to be reading HN in their break time :)