A few months ago the app store notified me to update xcode. When I attempted to do this, the download hung and wouldn't complete. I tried several more times after restarting each time. Always the same result of hanging.
Today I was annoyed with the app store still bugging me to update xcode along with the amount of disk space xcode consumes so I tried to uninstall it. I removed xcode it from /Applications and any other references I could find and emptied the trash. I cleared caches, repaired permissions, and more, restarting both the computer and the application several times. I even enabled the debug menu and reset the application. Despite all of this, xcode still wants to update even though it no longer exists on disk.
I'm running mountain lion. I'm not sure if I had xcode 4.5 or 4.6 because it's all gone now (except the app store doesn't know it yet).
Best Answer
Do you have a backup, or external drive connected, that may have something of the Xcode install on it?
I know on my machine, if I have my backup drive connected the MAS thinks anything on that drive is currently installed.