For some reason, neither Spotlight nor Alfred can find the Photo Booth app. The app clearly exists in the Applications folder, and it runs fine, but typing in Photo Booth to Spotlight only returns the folder that stores the Photo Booth images. Alfred just shows the standard "Search Google","Search Wikipedia","Search Amazon" that it shows when it can't find something. What's wrong and how do I fix it?
Your Spotlight index might be corrupted – Alfred uses the same index as Spotlight.
If Photo Booth is the only item missing, you can try dragging it out of
/Applications (to your desktop, say), then back in. You’ll have to authenticate as an administrator both times; Spotlight should pick up on it after that, and so should Alfred (after a small delay). If that doesn’t help, or other items are not found either, you will have to re-build the Spotlight index, either by following Apple’s official procedure, or via the Terminal command
sudo mdutil -E /.