I've noticed that some of the messages I leave on reddit's comment boards do not appear when I'm logged out. They only appear when I'm logged in under my username. To everyone else, they simply aren't visible.

For instance, try opening up two browers, say Internet Explorer and Mozilla Firefox. In the first browser, log in as usual. In the second browser, make sure you're logged out. Then leave a message on a comment board that is sure to get their moderators' attention. After a few minutes, view the same comment board in the second browser. If you got censored, your message will still show up in the first browser, but will have disappeared in the second.

It's a covert method of censorship, probably adopted by the guys who run reddit to generate as little controversy as possible, because the people who get censored are none the wiser. They think everyone can still read their posts, but in reality, the outside world doesn't even know they're there. There would be a massive outcry if its userbase knew how routinely they were being censored without their knowledge. I looked through all my previous comments and discovered that even the most innocuous messages get censored.

This has nothing to do with the number of downvotes that you get either. Comments that get downvoted beyond the viewing threshold still appear as a single-line "collapsed comment" that you can open up by pressing the "[+]" button.

Anyone notice reddit doing this to their comments or submitted stories too?