I just did a fresh install of Mountain Lion and I came across a probelm where I am trying to reinstall applications which I can find but in App Store it is listed as "Installed".
MacBook Pro, OS X Mountain Lion (10.8.2)
Make sure there are no external drives connected to your machine because App Store considers the App to be installed if it finds it on an external drive.
Also, try a reboot and then going into the store.
You are right about App Store consdering all Apps to be installed if it finds it. I realised what I did wrong, when I cloned over my freshly installed Mountain Lion on my external hard disk to my internal one, I forgot to ask it to overwrite my internal disk so the Apps must still be there and therefore showed up in App Store as installed. Thanks!
Which cloning utility did you use and are you sure it was not set to erase then clone?
If you didn't overwrite the disk, I'd just erase it and do again.
how to reinstalled a program that App Store list as "installed" apps
