Spell check doesn’t work 4.0.2.2 Linux Mint.
Trying the suggested fixes, no go.
It’s bad enough, I have to use Microsoft Office in Windows XP to spell check.
I know this is no help, but I’m running LibO Version 4.0.4.2 (Build ID: 400m0(Build:2)) on Linux Mint 13 “Maya” Xfce (LTS), and spell check works perfectly.
I don’t know much about these things, but I assume you have checked that the “language” of your text has the correct “dictionary” loaded and enabled? Check in Tools > Options... > Language Settings > Writing Aids:
You can see which “Language” LibO thinks you’re using, either in the Tools > Language > menu-flyout, or in the Status Bar at the bottom of the screen (might need to be enabled from View > Status Bar).
FWIW - hope that helps.