Of course it doesn't make you immoral. It is often a symptom of an already existing lack of or laxness of morals.
> Cussing does not make you immoral.... It is often a symptom of an already existing lack of or laxness of morals.
I would argue that an intentional lack of cussing denotes considerable immorality. Cussing is about the best way possible to express honest emotions; and hiding ones emotions is a form of dishonesty. Habitual dishonesty is generally accepted as immoral.
I do not trust anyone who is unwilling to express their true feelings.