I have tried
(set (make-local-variable 'comment-auto-fill-only-comments) t)
and also
(auto-fill-mode 0)
Though amazingly, neither of those work after emacs is restarted.
I am using eschulte's emacs starter kit
Toggling it works fine with M-x auto-fill-mode.
Using a combination of (thanks Rémi):
(auto-fill-mode 1)
(setq comment-auto-fill-only-comments t)
It works perfectly within programming files, where there are comments. However, in text mode, it auto-fills everywhere.
How can I turn off auto-fill-mode completely when inside text documents?
If you want Emacs to auto-fill comments you must not make comment-auto-fill-only-comments a local variable:
(setq comment-auto-fill-only-comments t)
If you want it only in some mode but not all you have to add it to the correct hook:
(add-hook 'ruby-mode-hook
(lambda () ((set (make-local-variable 'comment-auto-fill-only-comments) t)))
UPDATE answer
To remove auto-fill from text mode, you have to use hook:
(add-hook 'text-mode-hook
(lambda () (auto-fill-mode -1)))
Note that this will change also the auto-fill state in mode deriving off text-mode (latex-mode is one examples, there are a lot of other such mode)