After running into some significant (and now fixed) issues on Xbox Live Marketplace, it looks like there are still more kinks to be worked out of Xbox.com since the Xbox Live maintenance earlier this week. Tipster soulpopped reports that secret Achievements are showing up on gamercards, regardless of whether or not you've unlocked them yourself.
Specifically, the new Xbox.com shows three of the most recent Achievements unlocked on any person's gamercard. If one of those three Achievements happens to be secret, it will still show the full achievement description and image, even if the person viewing it hasn't unlocked it. If, however, you open the "Compare Games" section, the achievement is simply listed as "Secret," as it's supposed to be. If you're still confused, check out the images in the gallery below for a more detailed example.
We haven't been able to replicate the bug, as there's a slim chance that one of the three most recent Achievements unlocked by someone happens to be secret, but it's still worth noting if you absolutely hate to see any part of the gaming experience spoiled.
We asked Major Nelson if Microsoft has encountered this (admittedly minor) issue. We'll update this as soon as we hear anything.