"Mah" and its variations can be used to any emotion. Because of its short, blunt nature all one must do to change the meaning of the word is to change the style of how it is pronounced; also with appropriately added facial expressions. To express anger one must say "MAH!!" with the appropriate angered facial expression. Happiness is also expressed with "MAH!!", but with a slight lift on the 'A' rather than the the downward pitch of the Angry form. Indifference is shown with more of a "Meh" sound.
"Mah" is one the most versatile words in the english language. It can express almost anything as long as it is pronounced, emphasized, and coreographed correctly.
If your having problems expressing yourself with this wonder of a word, youre probably thinking too much about the usage. Just follow your heart and let the word speak for itself. The mah will never dissapoint.