Following discussion on vim/vim#1015 I returned to editorconfig idea whether it could be helpful to me. I am Czech and programmer by profession. Which means that I have a huge variety of projects with both languages. Most of my .vimrc files are just:

set spell
set spelllang=cs

(or spelllang=en-gb). That just switches on spelling for documents in given directory and sets the spelling language to Czech (or UK English).

I look at #293, but I agree, that it is too specific and exception files are hard to be done in the editor independent manner. However, the two lines I use are a way more manageable. Couldn't editorconfig plugins start to support at least these two, please?