Root users get all the fun. Case in point: there's a debug menu built into the Play Store APK, and only those with access to root can sneak a look at it. This isn't exactly a secret - the debug menu has been there for quite a while - but one of our readers brought an easy method for displaying it to our attention. You'll need root, the flexible Xposed Installer, and the "All Apps In Play Store" Xposed module.
First, install Xposed, grant it root permissions, tap the "Install/Update" button in the Framework section, then install the All Apps In Play Store module from rovo89 and make sure it's active. (This will require a reboot or two. I'll wait. Ready? Let's continue.) Open the Play Store Fixes module in Xposed and select "enable debug menu." Now just open the Google Play Store app and tap the menu button. You should see "debug options" in the drop-down list. If you don't, clear the app's data and cache in the Applications section of the Settings menu and try again.
So what's in there? Honestly, not much that will interest anyone except developers. You can display the size of downloaded images, which is information that's usually transparent, but it might be useful since many apps include screenshots of different sizes for different devices. You can skip caching for downloaded images, clear the Play Store cache, disable personalization, dump the library state, and enable a "fake" rating for testing purposes. There's also a carrier override option, though the Xposed module you used to get this far will open up any carrier-restricted apps anyway. If you want to spoof settings for other carriers, Google+ user Nikolay Elenkov has a simple method for doing so. The various network codes can be found on Wikipedia.
So there you have it. There's nothing in here that will drastically change the user experience of the Play Store. Feel free to check out these options if you're rooted, and if you're not, they probably won't inspire you to root your phone or tablet just to see them.
Thanks, Matthew Biggs!