Annoyed by text underlined with red dots? Tired of having to turn off spell checking every time for a particular application? Here is a quick solution to disable spell check in Mac OS X, derived from what I’ve found here at Dry Fish blog.
Apparently, “disabling” the system process AppleSpell.service by renaming it is not a good solution since you’ll keep getting the dialogs about the service not being able to be found. Dry Fish suggested renaming the language directory en_GB.lproj within the AppleSpell.service package. I did that, but found out that wasn’t good enough since the spell checker also checks spelling for other languages (German, Dutch, etc).
So all I had to do was to try and rename the whole “Resources” directory within the AppleSpell.service application, quit the AppleSpell.service process in the Activity Monitor and open any app that uses the spell checker (used Tweetie for Mac in my case) to bring back the AppleSpell process. No red dots anymore, finally. So here are the instructions.
AppleSpell.service is located in System > Library > Services. Right-click on it and select Show Package Contents.

You won’t be able to rename the Resources folder directly in Finder, so use Terminal and run the following line in it (you will need the administrator password!):
sudo mv /System/Library/Services/AppleSpell.service/Contents/Resources /System/Library/Services/AppleSpell.service/Contents/Resources.disabled
You should now see the renamed directory:

Quit AppleSpell.service process in Activity Monitor and bring it back on – by running any app that uses the spell checker. You’re done.

Disabling spell checking works in Snow Leopard. Re-activate spell checking by renaming the “Resources.disabled” folder back to “Resources”:
sudo mv /System/Library/Services/AppleSpell.service/Contents/Resources.disabled /System/Library/Services/AppleSpell.service/Contents/Resources
Cheers.
