If you know a language and would be able to use it in a professional setting but really don't want to, should you still put it on your cv to show the experience you have?

Depends; if your CV is filled with experience, leave it out. Stops you from showing up in recruiters searches for that language.

On the other hand, if your CV wouldn't die from some padding leave it in. Any and all language proficiencies are good to for future learning.